Turning off when unplugged

Hi guys,

I left my steam deck plugged in overnight so it would download rdr2. I have the battery protector on limited to 80% and when I woke up I saw it was at 99% which is odd. When I unplugged it, the deck immediately died and will now only turn on when plugged in. The battery % has dropped to 45 since then and the battery health is at 88% but when its plugged in it shows as "not charging" in desktop mode.

Anyone have any ideas?

Thanks!!