I had a similar experience with the 'Telo' - there's a thread on QRZ I started.https://forums.qrz.com/index.php?threads/ooma-telo-killed-by-rfi.495601/
Killed 4 of 'em totally dead before figuring out what was causing it (near field HF transmissions - 17M seemed the worst, for some reason). With the last one, I added some filtering - caps on the DC power, and on the phone line. I also added about 3 turns (all that would fit) on each of the Ethernet lines, in / out, through big junk box toroids (scavenged from an old PC power supply). The last Telo didn't die completely after RF exposure - the lights would still come on (sort of), but it didn't function. I offered to discuss the issue with the Ooma people - if there was an engineer available who know something - but was never taken up on the offer.
We switched to plain-old-telephone-service, on the traditional twisted pair. Reliable, but not as nice, nor as cheap.
Now, my wife wants to go back to Ooma. This means a more aggressive and effective filtering design is required. Mulling over the design options - especially on how to filter the Ethernet line (maybe have to connect the Telo after the router - so there's only 1 line to filter ? )