Well, the fact that the light flashes tells me the unit wants to work, but something is overriding it
That something could be the light curtain, the lock button, or something mechanical exerting more torque on the door then the opener can overcome
One more option could be the boy hit the "learn" button on the opener and he reset the codes (but that is very unlikely)
Have you tried holding the button down for 10 seconds, or using a remote?
