Is it really the screen or the motherboard? You may be able to tell better when you open the keyboard.

Adding a large number of media files in one go makes tracker go berserk. Tracker is a background process that indexes your media files. Depending on how many files you have added, it may take a few minutes to a few hours to finish indexing. The indexing process takes a lot of CPU power which explains the hot operation and a lack of responsiveness. I would just leave it to finish the job, overnight, on a charger as otherwise it would suck your battery dry. Just hope that you have not damaged anything by throwing it around and dismantling it.

If it is really the screen, then I fear a hardware fault. You may end up having to replace the screen, unless it is something trivial like a loose cable. But I must tell you this is the first time I hear something like that.