After using my TinyScreen+ for something else, then putting it back in the TinyTV case, video has these horizontal lines. Is the screen toast now?

Hmm, if those lines aren't just an effect from taking a picture of the OLED, it could have been damaged during re-assembly. The glass screen can be cracked without visible sigs of wear or tear necessarily and that can lead to a distorted display like you are perhaps seeing.

Usually when a screen is cracked or damaged, it'll have a distorted/erring display for a while and then eventually go blank. The hardware on the board will still work, however, and you can use the board as a processor and button board even if the screen is failing. It may be worth a shot to try re-uploading the TV program just in case something initialized incorrectly.

Let me know how it goes!

Cheers,
Réna

Yes, I see the crack now.