My fuser had to be taken out and cleared out because one or more sheets of paper had rolled into itself within the fuser assembly. It was painstaking to remove, but I got all the paper out.
But now when I put the fuser unit back in and close door A, I get stuck on the "Jam at exit, open door A" message.
No way to reset or get out of it (I have kept power off for days, so that doesn't solve the issue.)
Maybe I damaged some sensor while I was getting rid of the rolled paper from the fuser.
Many thanks for suggestions on getting out of this scenario (jam!).