I'm not too sure, but you have fried (that I know of) two SNES minis and three psone screens, and don't know what it is that's making them break. I'm going to go out on a limb and ask, how did you learn how to solder? Also, are you working on a metal surface or carpeted surface?
If you are working on a metal desk or plate, stop. I used an old metal computer case to solder on originally, before I knew that connecting voltage to ground would mess stuff up. If you are working on carpet, static build up could be frying your motherboards.
The only other thing might be your soldering. When I began modding, my soldering was really bad, I couldn't tell a good joint from a bad one, or if I accidentally bridged some connections. Where did you learn how?
I don't think Nobble would sell you a broken screen on purpose, he doesn't seem like a jerk. If you were able to get the screen to turn on at all, then I would check your soldering.