Yesterday, the power failed and I awoke to find that the TV
had turned itself on but no sound. Toggling mute and adding
external speakers did not work. I assumed the worst but
guessed that maybe this was a microprocessor locked into
mute. I unplugged the set and tried again after 15 minutes.
Sound was restored. Whew!

I've experienced this sort of failure with several items -- including an LV
player, a TV set, a PDA, and a DVD player -- over the past 25 years. I call
it "CMOS lockup", though whether that's the actual cause of the problem, I
don't know.

Basically, the product "misbehaves" in some way -- including apparent
"death". Removing the batteries or unplugging it, and then letting it sit
for a while, causes it to be "recalled to life" (Dickens). Sometimes you
need to yank the power cord while the device is running.

I don't know the exact cause, but I suspect it happens often enough that
people discard products that are otherwise perfectly good.