Satellite RBS 850 stopped working

I've been running an RBK 855 system with no major issues for 3 years.  A couple of weeks ago I noticed that one of the satellites was not working and was appearing as "Disconnected" in the Orbi app.

I tried restarting the router and all of the satellites but nothing changed.  3 satellites were all working as expected, but the 4th would not connect according to the app.  I tried bringing the problem satellite into the same room as the router and re-syncing it, but that didn't appear to do anything.

I then tried factory-resetting the satellite.  I used a paperclip to hold the reset button in for 15 seconds and saw the small status light was flashing amber.  Once the satellite restarted I attempted to re-sync the satellite again; I waited for a solid white light on the satellite, then pressed the sync button on the satellite and pressed the sync button on the (add a satellite) webpage and saw the router pulse a white light.  After a while the satellite light went to solid blue for a bit and then off, but still this single satellite does not appear as a connected device, or in the network map in the app.  All other satellites are working fine.  Is there anything else I should try or is it the end of the road for this unit?

Thanks.