Forma needs force reset after charging

This is weird. Every time I leave my forma on the charger for more than a couple hours, the battery percentage on the screen freezes at 96 or 97%, and the device is completely unresponsive until I hold the power button in for 15-30 seconds, I haven’t timed it, but long enough that the white light starts flashing and it takes a long time to boot up. The battery is usually 100% once it finally boots up, so it must finish charging after it fills up.

Has anyone run into it?

Doesn’t matter whether I’m reading a side loaded book or one out of the kobo store, if that could be an indicator.

I mostly load through Dropbox rather than calibre now. I don’t trust the microusb slot not to break if I’m plugging and unplugging things - I use a magnetic charger (a little nub that lives in the microusb slot and connects to a cable via a magnet - no strain and the cord won’t get twisted up if reading while charging.