Is it possible to downgrade to 4.1.13?

Downgrading is generally safe (and should be in this case). You will lose the shellshock security patches though.

It is possible that the OS partition is filling - If you have ssh enabled, you can check the OS fullness directly. If not, perhaps try deleting all the logs (backup included)? I'd try that before downgrading (and downgrading could fail if the partition is in fact getting full).

Thanks. My OS partition is ok (thanks to mdgm fixing it up after the 4.1.14 upgrade went awry for that very reason). I'm torn between downgrading, waiting for for the next patch, and clean installing. The standout feature of the NV+ over a home rolled solution is almost literally never having to worry about it for the ~4 years it's been running. Having it being a bit flaky is a weird and disconcerting experience.

A factory reset/rebuild could help, since perhaps there were other side effects from the full OS partition. Or maybe try an OS reinstall first, as that won't impact your data. Perhaps mdgm has a thought on that.

Hmm. So after a reboot, I'm in the same position. Can't SSH (connection refused by remote host) and can't get FrontView to load. I can't be entirely sure (until I can ssh) that I don't have a rouge backup process somewhere writing to the OS partition, but I'm fairly sure that's not the issue.

The activity light is flashing like crazy, the power button doesn't light up the LCD like usual. Short of praying for mdgm's remote fiddling ability, is there anything I can do to kick it in the guts?