So I’ve submitted an online support request to the company, and got a canned response telling me to do all the things I did yesterday. The thing is —
it works okay if it’s been plugged into the computer, and then allowed to “rebuild” the library. Once you turn it off, though, it stays off. It freezes at that same screen again.
So, moral of the story: never buy a Sandisk mp3 player. Or, if you do, keep the receipt handy. You’ll need it.