This question is from a coworker (say “Hi,” Nancy!). The other night, while watching a DVD with her daughter, they heard a loud “pop,” like a light bulb popping or plastic breaking under strain. They lost the image from the TV, but it remained lit up. They couldn’t turn the TV off, not with the remote and not with the power button on the TV. She finally turned her power strip off and back on again, and the TV, DVD player, and remote worked fine after that.
So WTF happened? FWIW, they live in an old house with old wiring, and their town has somewhat … idiosyncratic power.
It sounds kind of like an unintended high-voltage arc discharge–possibly from a damaged cathode wire. It would make that loud pop sound, and possibly scramble the circuitry temporarily (or even pemanently, if the arc goes to the wrong place). I’ve seen similar symptoms from lightning-induced surges, where the device starts operating erratically, until it’s power-cycled.
From your description, it’s really hard to tell without opening the unit up, sounds like something arced inside the TV and the surge knocked out an electronic component somewhere in the path that takes the antenna or cable signal and turns it into instructions for the electron guns to draw the picture on the screen.
It could have been a critter, or a piece of debris that initated the arc. Or it could have been a failure of some insulation. Either way, carbonization from arc-induced combustion likely cut off the conductive path for the arc again.
You see this a lot with electronics, especially digital, where a transient induces a change in the operation of a circuit. It happens because the unusual combination of voltages turns on a conductive path that is not usually turned on. Turning the power off and on again restores the normal arrangement of things.
If it doesn’t happen again, then it was probably a critter, or something one of her kids dropped in the back of the unit. If it does happen again, she should have the unit serviced.