I was trying to get my board back to using the onion2lte OS after I got it to the most recent OpenWRT OS. I found the image file for the omega2lte OS, and I put it on my board. Because I had trouble using scp, I ended up putting it on the board by making a github repository and downloading that with git clone. Because of that, it was not in my tmp folder, which I think might be the cause of my problem. I ran sysupgrade on it, and when it failed the image check I used the -F tag to force it. Now, when it boots, it will briefly show the OnionOS banner, then it says the following:
Board: Onion Omega2 APSoC DRAM: 128 MB
relocate_code Pointer at: 87f60000
flash manufacture id: ef, device id 40 19
find flash: W25Q256FV
*** Warning - bad CRC, using default environment

============================================
Onion Omega2 UBoot Version: 4.3.0.3

ASIC 7628_MP (Port5<->None)
DRAM component: 1024 Mbits DDR, width 16
DRAM bus: 16 bit
Total memory: 128 MBytes
Flash component: SPI Flash
Date:May 12 2020 Time:21:55:16

icache: sets:512, ways:4, linesz:32 ,total:65536
dcache: sets:256, ways:4, linesz:32 ,total:32768
CPU freq = 575 MHZ
Estimated memory size = 128 Mbytes
Resetting MT7628 PHY.
Initializing MT7688 GPIO system.
wifi mac address = 40A36BCB81DD.

• Hold Reset button for more options *

Boot Linux from Flash NO RESET PRESSED.

Booting image at bc050000 ...

Image Name: MIPS OpenWrt Linux-4.14.81
Image Type: MIPS Linux Kernel Image (lzma compressed)
Data Size: 1617461 Bytes = 1.5 MB
Load Address: 80000000
Entry Point: 80000000
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
No initrd

Transferring control to Linux (at address 80000000) ...

Giving linux memsize in MB, 128

Starting kernel ...

[ 0.000000] Linux version 4.14.81 (root@e0e82ebe349f) (gcc version 7.3.0 (Ope nWrt GCC 7.3.0 r0+7497-fc32c3afe0)) #0 Sat Nov 19 01:56:43 2022
[ 0.000000] Board has DDR2
[ 0.000000] Analog PMU set to hw control
[ 0.000000] Digital PMU set to hw control
[ 0.000000] SoC Type: MediaTek MT7688 ver:1 eco:2
[ 0.000000] bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 00019655 (MIPS 24KEc)
[ 0.000000] MIPS: machine is Onion Omega2 LTE
[ 0.000000] Determined physical RAM map:
[ 0.000000] memory: 08000000 @ 00000000 (usable)
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 byt es
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000000000000-0x0000000007ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x0000000007ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000007ffffff]
[ 0.000000] random: get_random_bytes called from start_kernel+0x8c/0x474 with crng_init=0
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 32512
[ 0.000000] Kernel command line: console=ttyS0,115200 rootfstype=squashfs,jff s2
[ 0.000000] PID hash table entries: 512 (order: -1, 2048 bytes)
[ 0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] Writing ErrCtl register=0006f893
[ 0.000000] Readback ErrCtl register=0006f893
[ 0.000000] Memory: 124580K/131072K available (3708K kernel code, 207K rwdata , 920K rodata, 212K init, 205K bss, 6492K reserved, 0K cma-reserved)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS: 256
[ 0.000000] intc: using register map from devicetree
[ 0.000000] CPU Clock: 580MHz
[ 0.000000] timer_probe: no matching timers found
[ 0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_i dle_ns: 6590553264 ns
[ 0.000012] sched_clock: 32 bits at 290MHz, resolution 3ns, wraps every 74051 15902ns
[ 0.007674] Console: colour dummy device 80x25
[ 0.011933] Calibrating delay loop... 385.84 BogoMIPS (lpj=1929216)
[ 0.073505] pid_max: default: 32768 minimum: 301
[ 0.078195] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.084537] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.098573] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, ma x_idle_ns: 19112604462750000 ns
[ 0.108067] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 0.114015] pinctrl core: initialized pinctrl subsystem
[ 0.119593] NET: Registered protocol family 16
[ 0.156039] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.161697] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.167223] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.173879] i2c-mt7621 10000900.i2c: clock 100 kHz
[ 0.183437] clocksource: Switched to clocksource MIPS
[ 0.195523] NET: Registered protocol family 2
[ 0.200670] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.207419] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.213523] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.219787] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.225420] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.231693] NET: Registered protocol family 1
[ 0.250215] Crashlog allocated RAM at address 0x3f00000
[ 0.256832] workingset: timestamp_bits=30 max_order=15 bucket_order=0
[ 0.269154] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.274772] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORIT Y) (c) 2001-2006 Red Hat, Inc.
[ 0.294793] io scheduler noop registered
[ 0.298524] io scheduler deadline registered (default)
[ 0.304565] Serial: 8250/16550 driver, 3 ports, IRQ sharing disabled
[ 0.311900] console [ttyS0] disabled
[ 0.315400] 10000c00.uartlite: ttyS0 at MMIO 0x10000c00 (irq = 28, base_baud = 2500000) is a 16550A
[ 0.324121] console [ttyS0] enabled
[ 0.324121] console [ttyS0] enabled
[ 0.331117] bootconsole [early0] disabled
[ 0.331117] bootconsole [early0] disabled
[ 0.339924] 10000d00.uart1: ttyS1 at MMIO 0x10000d00 (irq = 29, base_baud = 2 500000) is a 16550A
[ 0.349586] 10000e00.uart2: ttyS2 at MMIO 0x10000e00 (irq = 30, base_baud = 2 500000) is a 16550A
[ 0.359119] cacheinfo: Failed to find cpu0 device node
[ 0.364371] cacheinfo: Unable to detect cache hierarchy for CPU 0
[ 0.371327] spi-mt7621 10000b00.spi: sys_freq: 193333333
[ 0.390934] m25p80 spi0.0: w25q256 (32768 Kbytes)
[ 0.395803] 4 fixed-partitions partitions found on MTD device spi0.0
[ 0.402243] Creating 4 MTD partitions on "spi0.0":
[ 0.407123] 0x000000000000-0x000000030000 : "u-boot"
[ 0.413113] 0x000000030000-0x000000040000 : "u-boot-env"
[ 0.419427] 0x000000040000-0x000000050000 : "factory"
[ 0.425475] 0x000000050000-0x000002000000 : "firmware"
[ 0.524770] 2 uimage-fw partitions found on MTD device firmware
[ 0.530798] 0x000000050000-0x0000001dae75 : "kernel"
[ 0.536780] 0x0000001dae75-0x000002000000 : "rootfs"
[ 0.542588] mtd: device 5 (rootfs) set to be root filesystem
[ 0.549854] 1 squashfs-split partitions found on MTD device rootfs
[ 0.556196] 0x000000980000-0x000002000000 : "rootfs_data"
[ 0.563690] libphy: Fixed MDIO Bus: probed
[ 0.577609] rt3050-esw 10110000.esw: link changed 0x00
[ 0.586194] mtk_soc_eth 10100000.ethernet eth0: mediatek frame engine at 0xb0 100000, irq 5
[ 0.594886] i2c /dev entries driver
[ 0.600287] NET: Registered protocol family 10
[ 0.609052] Segment Routing with IPv6
[ 0.612894] NET: Registered protocol family 17
[ 0.617519] 8021q: 802.1Q VLAN Support v1.8
[ 0.626075] squashfs: SQUASHFS error: unable to read id index table
[ 0.632765] jffs2: Flash size not aligned to erasesize, reducing to 30848KiB
[ 0.640575] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000000: 0x7368 instead
[ 0.650253] jffs2: jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000004: 0x087f instead

And it will repeat some variation of that last line for about a minute before it reboots and starts the process again. I can only connect to my board via serial on Putty, and at no point in this process can I put commands on that terminal. What I'm wondering is did I brick this board, or is there some way I can fix it over serial?

Well that would be the problem, I was using the serial port. However, the device I was originally trying to use doesn't need RS232 (it can be connected directly to an arduino uno). I'll convert the signal to RS232 for the purposes of debugging, and hopefully that will illustrate how to solve the problem. Will installing the OpenWRT 18.06 let me get the LTE OS back, or do I have to find it specifically some other way?

I have tested the serial output with the echo command with the most recent version of OpenWRT, and it has the same problem, so the problem doesn't seem to be a problem with the LTE OS

So I tried that. After it installed, I couldn't access the board's wifi network or access the board on my own wifi network. I connected to it via serial, hit enter, and was in a terminal that was specifically openwrt, instead of onion omega. I tried to use wifisetup, but that command didn't exist, and when I tried to use other wifi commands it had, it said ''radio0' is disabled' twice. I tried to factory reset it with the direction on the docs, and on the reboot it briefly shows the onion terminal banner before saying
'*** Warning - bad CRC, using default environment'
and continuing to the openwrt boot. Is there any way to use this normally, or at least factory reset it, or do I just need a new board?

Okay, so I think I figured out what you are supposed to do. You can download the sysupgrade to your computer, than transfer it to the board with the scp command, then run sys-upgrade (this short tutorial covers what you do once you download the sys-upgrade file https://www.youtube.com/watch?v=VgSVg3xFfUo&ab_channel=TechLevelJedi). When I try this however, regardless of which sysupgrade I choose (onion omega, onion omega2, or onion omega2+), when I try to run sysupgrade, I get the message:
"Device omega2lte not supported by this image
Supported devices: onion,omega2 omega2
Image check 'fwtool_check_image' failed."

The devices under "supported devices" changes depending on which one of the three I use, but none of them seem to support the omega2lte. Is there a way to get an upgrade that is compatible with the omega2lte, or am I doing something else wrong?

The OpneWRT version is 18.06-snapshot

The Onion firmware version is v0.3.3 b251
And the onion os version is 1.0.6-1

I'm trying to upgrade my OpenWRT in the Onion 2lte by following these steps, but I'm not sure where exactly the src directory I should be deleting is. Also, when I get the kernel or sysupgrade from the image downloader, what do I do with it?

Linux Omega-81DD 4.14.81 #0 Fri Jun 4 20:35:27 2021 mips GNU/Linux

I don't know exactly. I looked up how to find out, and it said to run
cat /etc/banner
which just shows the startup banner. The banner says Ω-ware: 0.3.3 b251 but I'm not sure what part of that, if any, is the version

I don't think the problem is with the other device, considering I have tested it with other serial devices and it works fine. Similarly, I have another device that can take serial input which does not work properly with my omega2lte board (that device doesn't display input data that isn't in the correct format, which is why I have to use the other thing to troubleshoot). Is there some reason why it might have trouble sending to other devices in general? The only thing I can think of is if it isn't using RS232, and if that's the problem, is there a way to get it to transfer with that protocol?