Here's a fun and easy one to fix.
One commodore plus/4. Here's what it displayed.
Looks like the TED chip is outputting something, but it isn't setup right.
So I pop it open. There's the right clock on pin 1 of the CPU - switching between 1 and 2MHz as it does. Ok, so let's check the ICs.
Hm, there's something wrong with the CPU pins.
And this socket ... is kinda busted looking. One whole side of pins just aren't making contact correctly.