One of my 3 Sears Crafsman 1/2 hp garage door openers is not working. It is
stuck in the open position, so I closed it by releasing the emergency
handle.

The trolley is firmly wedged against the cover protection bolt instead of
having stopped at a normal 2 - 4 inches short of the bolt. The small length
of chain on one side of the motor just before the cable feels extremely
tight and won't budge, while there is a little play in the chain on the
other side of the motor (the long length of chain). Also the indicator
light next to the button for changing the remote code is blinking.

When I press the button in the garage to close the door, the motor hums for
a couple of seconds, then stops humming, but the trolley won't move.

The manual isn't clear, and I'm guessing the issue is straightforward, I'm
just don't know what the issue is.

Please advise.