my canon 1d mkii n sometimes works fine but fires and focus fast as it should it has around 134k shutter count so a bit of life left in in yet I would think, on other occasions err99, appears the shutter might stay open too long or the buttons wont work.i have tried taking out the batteries including the little one for the clock ect cleared the custom settings
Not sure what your problem with the camera is. But I have one and the shutter died around 70k….they can go sooner than Canon say. Err99 tends to be a catch all problem, could be a range of things. Send it to ISS Canon to service it.
I spoke to iss via email there is not much they can do because of lack of parts for repair if a shutter has seen better days does it stop working or would it work some times since I started this post the camera has worked fine but there is no trust in it. Also the shutter wouldn’t explain the display or settings not working so im leaning towards to processer