Re: Canon 1D with flashing "Err", yet no code
Sorry to hear of this problem. Based on your description, the most likely scenario is that the shutter mechanism has failed. This could happen for any number of reasons, including the number of actuations (i.e., how many exposures have been taken by the camera with that shutter), etc.
Beyond that, though, the bigger problem is that Canon is no longer offering repair service for the original EOS-1D, mainly due to lack of service parts like shutter units, etc. It's essentially a 9 or 10-year old camera at this point. You can try to have the camera serviced through an independent authorized service facility, but that is up to you. If the camera cannot be repaired, it might be time to replace it with a newer model.
Professional Engineering & Solutions Division
ITC Group/Canon U.S.A., Inc.