The maker may be able to tell you how to fool the opener into working again.
You could also try quickly blocking the door from coming back down with a piece of lumber; the opener should sense this and go to some fail-safe state, 'state' as in 'state machine'.
Your opener and the phone system and motion detectors and spacecraft and dishwashers and furnaces and vending machines can be viewed as state machines
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and sometimes only the maker knows how to get them into usable states from 'illegal' states. Yours seems to be in an illegal state and maybe it got there due to a power quality problem or a design defect.
Along these lines, I suppose you could cut power to the opener, wait >15 seconds and then restore power, in hopes of resetting the opener's computer.
It could also be legitimately responding to a blockage on the track or some mechanical failure. The maker can step you through a troubleshooting procedure to isolate the problem.