Canon 5D Mk3 Access Light Issue

[maddypix18]

Hello Canoners...

I am having this weird issue with my 5D Mark 3 which i bought from FB Market Place . Shutter cound (~500 only)

I see that my Battery draining very fast evn when camers is in OFF - eg: i kept a fully charged battery and powered off and overnight battery becomes dead.

I noticed that "Access Light" on the bottom right hand side is keep on blinking even when the camera powered off , i am suspecting that could be the cause for battery draining. Not sure how to fix this. 

I already tried reformatting my SD card as this could be a write error, but nothing helps. 

Any help would be really appreciated. 

thanks

Maddy

[MikeSowsun]

Does the blinking stop when there is no card in the camera?

I would try leaving it overnight without the SD card or CF card in the camera.  If it doesnt discharge, I would try another card. 

If it still discharges with no card, or a new card, I would expect the camera needs to be serviced.