The EOS 6D was released in 2012 as Canon’s first consumer-level, full-frame DSLR. It comes pre-equipped with a 2.75”x2” LCD viewing screen, a GPS antenna and wifi connectivity.
you already have tried removing and reinstalling the battery so I think there isn't anything you can do. But that's an expensive camera so try and put it the some shop that can look it up for you.
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