my Omega2+ will "shut down". I can't access the Wifi AP and the LED is off.
If you find your board in the state you described again, before you do anything with it try probing the SPI lines with a logic analyzer. If you see activity it means that your Omega2+ suffered an unexpected reboot and the SoC primary bootloader is trying to load U-Boot using 3-byte addressing, but the SPI flash is still configured to use 4-byte addressing. (refer to Omega2 reboot for more info on this issue). If this is the case you have to power-cycle the board in order to get it to boot again (which resets the SPI flash addressing to 3-byte mode)