I don't know what the 24 hour charge does, but it seems the device is back to working perfectly now! I read for 3h over the last 20 hours, most of it with the backlight set to maximum just to see how the battery reacts, and even did a firmware update in between the reading. Its dropped to 96% (firmware update took it to 97%, and 1% is everything else) ...
I am going to observe it for the next few days, to ensure it truly is all good again, but I feel quite happy right now
Just hoping that it doesn't suddenly drop from the 90s to 20% or something in a few days ...
Anybody know what the 24h charge actually does?