I am in a similar situation.
I have done factory reset many times, and firmware reset a few times. I get about 15min before reboot. After reboot I can reconnect (wp6.sh) and sign in at the GUI, but anything involving wlan1 will not work until the unit has been without power for some time (cool down? although it does not feel hot). Since it seemed like a power issue initially, I have been giving it as much as I can (Y-cable to the ETH port, from the hosting laptop(kali), Y-cable to a powered USB hub (with no computer hooked up to it) to the UART port, and the AC wall adapter. The system log in the GUI seems to only show results for the current session so its hard to see what may have caused the reboot (if there is a to log SSH to on the system that may show more that would be helpful)
So, I too am at my wits end. Ive tried a different computer, again with Kali installed, and everything seems to be pointing me towards the hardware.
In my most recent attempts I have just been starting it up, starting PineAP and just let it sit until it goes into a reboot (which I just watched it do)
If there is anything I am doing wrong, anything I should try, or if this looks like a problem with the hardware I would appreciate hearing about it.