Blinking red light for charger, no power-on

[bifo]

I've checked through the threads on this and so far attempted checking the battery connections.  I have a late summer 2020 pinebook pro which has been fairly reliable (aside from software boot issues) since receiving it, upgraded with a 128gb EMMC and an intel 660 NVME 512 drive, the latter working for several months now.  I left it plugged in yesterday after having it compile a lot of software on the Manjaro install on the EMMC, and discovered it dead.  The red light will blink, the green light even goes on if I leave it for some hours, but after checking the battery connection (I don't move it much at all, but it was suggested in an old thread) it still blinks as if it can't accept charge signals.  I've been charging it via both USBC and the AC adapter, no problems for months.

Any suggestions or questions for further troubleshooting?  The NVME doesn't actually get used until I run a shell script once logged in.