@Higor which uboot version are you using?

@crispyoz Sorry for the time it took me to reply, I got it working in my docker and it works well enough but thanks for the help

@markimpgs have you plugged the Omega2+ into your computer USB? Here is a thread on how you can mock up an ethernet connection without the use of a dock. https://community.onion.io/topic/1964/omega-2-ethernet-without-ether-dock?_=1632597620423

@Nagarjuna-Reddy This is the document I was referring to, so I think it is important to check that when you do a reboot that these pins are actually in the required state.

@cspensky take a look at this tread. https://community.onion.io/topic/4330/unable-to-flash-firmware-from-usb/12?_=1612513950216 @tjoseph1 has a nice solution

Hi guys. Thank you everybody so much for all these answers, it is so nice to see that the community is still really active. I come back on the problem after a few months because I would really like to use this Onion again. Now when I connect it to the USB the computer detects it but in serial connection nothing happen and the ligh on the Omega doesn't even turn on. I bought a CH341A to flash it with SPI, there is someone that knows how should I do it and which firmware should I flash? (Sorry but I've never done an SPI flash before)

@jmztaylor Well that's good news. I suspect your USB key probably has an issue if you cannot mount it. You could likely fix it so you could mount it by running chkdsk on a windows machine or using dostools on a *nix machine. I just add those comments for future readers of this thread, but the core issue you were having would be as I detailed above.

Hi @crispyoz, thanks for helping... I'm trying to build a fresh original u-boot with I2C support enabled. So I need to rebuild official u-boot because I cannot find any evidence of I2C support in Onion bootloader Ralink BootLoader 4.3.0.3 (the same you linked). I found Omega2p dts files in OpenWrt source code: openwrt/target/linux/ramips/dts/OMEGA2.dts openwrt/target/linux/ramips/dts/OMEGA2.dtsi openwrt/target/linux/ramips/dts/OMEGA2P.dts I think one possibility to build the official U-Boot firmware for Omega2p is to create a new board configuration using this two: gardena-smart-gateway-mt7688_defconfig linkit-smart-7688_defconfig Do you think I'm on the right track? Thanks a lot Alex

Original poster is right. looks like a bug in the boot ROM. It wants 120,000 baud rate, not 115200. Context: Omega2+ in mini-dock, Win10 64 bit, trashed file system, want to go back to factory firmware. Wifi connectivity also trashed. Holding the reset button down for 10 seconds does not work, still trying to boot from the micro SD card So I wanted to update the firmware from a USB stick, following the procedure in the documentation. I inserted the USB stick. Holding down the reset button while turning power on, the serial port disconnects soon after power-up. Only way to recover is disconnect and reconnect USB, but this forces a power cycle. No good in the mini-dock. Tried the same process in a Linux system, silent failure this time but still no luck. Move to a Power Dock 2, soldered on a SparkFun Serial Basic card (CH340). Made sure it was jumpered for 3.3V! Pins 1 gnd 5 Tx 6 Rx (seen from serial card end) . Note - you can't do this with a mini-dock etc. because your external serial card will be fighting with the internal serial converter chip. Now it comes on with reset button held, but screen full of trash for 40 seconds then a normal boot. Then I came across this comment, inspiring me to try 120000 baud rate instead of 115,200. Works! Procedure - set PuTTY for 120,000, power on holding reset button until fast blink, zip over to the keyboard and hit 2 quick as a bunny, system loads from USB stick and then does normal boot. Switch PuTTY back to 115200, hit enter and the prompt shows up. Don't know why it skips the log-in or why it needs a carriage return. But that has been my experience with this system using the hardware serial port. There seems to be no other way to unbrick a non-WiFi capable Omega2, except maybe if you have an Ethernet dock. Probably same problem trying to use a micro-SD card.

@Ary-Vinicius--Nervis-Frigeri Please. Some detail would be very-very nice. You have an Omega2(?) FW v0.?.? ???, an Arduino Dock 2, a host PC with some OS ??? and with Arduino IDE v1.?.?, ... You want to flash some bootloader into the on board ATmega chip. Which one? BTW what does "recover" exactly mean for you in this context? Thank you.

@Douglas-Kryder for what? Pine is just simple dev board, ok, raspberry shows the same error, should I go to raspberry forum? I use flashrom, pine64 is connected by spi, and is used for communication only upd: I resized uboot.bin up to required size and flashed it without errors, tomorrow I will solder it back to omega2 and test it

The flash is not a BGA - you can clearly see all 8 contacts in the picture, and if you hold the MT7688 in reset it will stay out of the way of your programmer. But you have to remove the shield. Unfortunately, JTAG does not seem to be available without removing the shield either. If you want to do low-level work you'd likely be better off with a Linkit Smart or an ACSIP module than an Omega2, in both cases where removing the shield is both less necessary, and substantially easier.

@Chris-Stratton Yes, I'm aware that a "hard brick" is possible Can you share the information on how it's possible to change the UART Port for U-Boot?

I reflowed omega2 but it didn't fixed it.. It still saying it only has 64k RAM.. I think I damaged PCB while removing EMI shield.. Well, thanks everybody.