The little 7" LCD I had connected to my router went dark a few months ago. I replaced it with a spare (which, annoyingly, required a VGA-to-HDMI adapter) and put it in a drawer with its power supply.

I came across it today while cleaning and decided I should investigate.

First order of business: does the power supply supply power?

Multimeter said no.

Opened it up.

Well, at least the problem was obvious.