Why my 6D canon is dead and wont come back to life?

while the camera is on and using it, the screen suddenly turned off, and when I check the upper monitor, its says err, BLT I turn it off immediately. when I turn if it on again, i heard the shutter turned on but no display in my screen then I turn it off and on again their was no life at all. My 6D is dead. pls help me fix the issue..