Nikon D800 power issues (or battery issues)

I purchased a Nikon D800 with a shutter count of around 4000 2 years ago, and it's at around 35k now. Everything has been going great with the camera until recently. The other day, after i had the battery on charge for 36 hours at one time (i forgot abt it), i popped it into my camera, took maybe 2 or 3 pictures, then set it down until the next day when i found the camera completely lifeless, not even a dead battery icon. I popped the battery back into the charger, used it a little more, and today i topped it off before taking it to a football game, where the camera went lifeless again after about 2 hours, just suddenly. no error, no dead battery icon, just bricked. but, after plugging the battery in again for maybe 5 minutes, it powered on and read a charge of 95%, which is suspiciously high.

Does anybody have any theories as to what's going on here? Anything is greatly appreciated!!

https://redd.it/1xjy0zf
@NikonBackup

Nikon z6iii with tamron 90mm macro..
https://redd.it/1xk1l8o
@NikonBackup

Primes are dead to me | 24-70 2.8 S II

https://redd.it/1xk4g4e
@NikonBackup

Tiny mushroom
https://redd.it/1xk4qus
@NikonBackup

Practicing bird photography with Nikon D3300

https://redd.it/1xk51au
@NikonBackup

Finally got Nikon Zf 40mm f2

https://redd.it/1xjv188
@NikonBackup

Misty morning in Cambridge - Z6 and 40 mm f2
https://redd.it/1xk81nu
@NikonBackup

These people really know how to run a business[F100/AF-S 28-70mm/Lucky C200,Harman XP2]

https://redd.it/1xk9cvb
@NikonBackup