SRR60 breathing/pulsing white and zero connectivity

Down to a last-resort-post here before the router and satellite get junked. 

Woke up this morning to no connectivity to the router, satellite was still broadcasting SSIDs but had no connectivity to the router (purple halo)

Gave it a while, rebooted, and it's been downhill ever since.  Immediately upon power-up, the power LED goes directly to green and the halo flashes white.  After a short period of flashing it then transitions to 'breathing' or 'pulsing' white and that's it.  No SSIDs, no connectivity, just a slow.. white.. light.. 

Most things posted, I've tried. 

• Reboot?  Check!
• Reset via holding reset button until amber light flashes? Check!
  • When I release the reset button, the power LED goes dark, the breathing halo continues and nothing.. for up to 1 hour.  Power cycling return the power LED to green, the halo to breathing white, that's it.

• Got a bigger hammer, full 30-30-30 reset
  • Held reset for 30s, keep holding reset and unplug and wait for 30s, still holding reset plugged back in and waited another 30s
  • Result here is a flashing red/orange power LED. 
    • Attempted 3 firmware updates (2.7.2.102, 2.7.3.100 and 2.5.3.110) via TFTP (all successfully delivered)
    • Each time during the process the halo turned off and the Power LED went green, but there was no indication of firmware progress or updates taking place.  After more than an hour of waiting, power cycle returns me right back to square one.

When the router and the satellite are powered up at roughly the same time, the router does its slow breathing white light and the satellite follows suit for a short period before it actually turns purple.  If I hit the sync buttons, the router shows zero interest in cooperating while the satellite flashes purple a few times and then goes dark.  I presume the satellite is actually able to connect to the router, but the router has decided it wants no part of being a functional piece of technology anymore. 

Test config:

Router is connected to the same switch as my PC (Win10), TFTP connectivity is solid and a ping -t doesn't drop any packets as long as the power LED is flashing red/orange.

I have connected the router directly to my PC as well, zero difference in behaviour or outcome.

Satellite is fully wireless, except of course for the power, and is in close proximity to the router (anywhere from side by side to about 5 feet away)

This has been a very reliable mesh network for us for a few years now and while we have entertained the idea of moving to a WiFi 7 mesh network (maybe it heard us and threw a fit? lol) it's a little cost prohibitive at the moment - Suggestions won't be ignored! 🙂

Thoughts or ideas are welcome, while I'm reasonably tech savvy.. I've basically played out anything I can think of at this point.