I have the same issue as this thread: https://www.arednmesh.org/content/untested-hardware-nanostation-m2-and-32030
I'm using two identical units. Both were flashed with aredn a few years back and were working as recently as last week. Decided to upgrade to latest version. First one went off without a problem. Used sysupgrade and upgraded to 3.22.1 (aredn-3.22.1.0-ath79-generic-ubnt_nanostation-m-squashfs-sysupgrade). It works fine.
When I did the second one, the RF did not come back on and I knew there was an issue. I finally found it at 192.168.1.1 with the "untested hardware" banner. Here is the support dump:
I eventually used TFTP to take it back to aredn-3.19.3.0-ubnt-nano-m-factory.bin and it recognized the board and worked as expected. However, if I tried to upgrade via sysupgrade it produced the same issue (board unrecognized).
One option, and this would be a test, is to reload AirOS to the device. Then from AirOS UI reload AirOS again. This 2nd step will update more things in the flash, including the boot loader. Then reload AREDN firmware. Something is not right with the flash data on this device, but we're in uncharted territory if, or how, this vender information in flash can be recovered. In the prior instance, we never really knew why it suddenly started working.
Joe AE6XE