Error 05, menas the camera detects that the built-in flash has not reached its normal, raised position for flash shooting, and is halting operation until the obstruction to the flash is cleared, or the flash is pushed back down to its OFF position.
It is stuck. You can help it to pop up with your fingrernail in the crack. Then you need to clean the linkage with a q-tip and denatured alcohol. You can put a "drop" of WD-40 on the hinge if needed. This means a drop not half a can. A little is good but more is not better.
EB
EOS 1DX and 1D Mk IV and less lenses then before!
