5D Mark III weird issues.

[Swerky]

Hello all. 
I had accidentally stored a camera (5D Mark III) while still being turned on. It was on auto sleep. If I remember correctly it still had two bars on the battery. Two days later I picked it up and the battery was drained. So I turned it off and replaced the battery. When I insert the battery, the light doesn't blink. I turn the camera on and it blinks and the camera takes a shot by itself. The start/stop button doesn't respond unless I half press the shutter button. The shutter button doesn't respond unless I'm on menu or playback and it immediately takes a shot at half press. Menu and play buttons don't respond unless I half press the shutter button. It shoots video normally. I had reset the camera settings, updated firmware, removed and inserted battery. Tried another battery. Same situation.
Would anyone know anything about this situation?
Thank you.

[wq9nsc · Accepted solution]

I would remove the battery for 10 minutes or so and also remove the lens and the memory card.  Now install the battery and see if you get a normal power up and then try it with your lens and memory card in place.

"Smart" electronics behave oddly when the supply voltage drops below normal but stays above zero as it does with a drained battery. 

As I recall, the III doesn't use a backup battery for the time/clock but instead stores some data via a "keep alive" low leakage capacitor providing backup power; this type of scheme recharges the cap when the battery is installed.  It is possible that bad data was stored during the battery rundown and if so you would have to patiently wait weeks for this capacitor to discharge or send it in for service.

Rodger

[Swerky]

Looks like I need to have it serviced since your suggestion hasn't worked. I'll make sure to relay your precious information as well. It'll prove helpful. Thank you!