Response from Jonathan: A: Why is the screen looking so messy with lots of artifacts on the screen (the original problem)
This does look like it could be related to some chips on your board. With that said, this is probably more of a RAM chip problem than a ROM chip problem. Might try replacing some of the RAM chips and see if it makes a difference.

B: Did I mess up that chip? I keep inserting and removing but it keeps beeping and failing on the chip test which it didn’t do until I removed it. Doh!
You could have messed up the chip. It’s easy to break a leg when trying to remove a chip or reinsert a chip incorrectly causing a bad connection with the board. Good news is that you should be able to get a set of replacement ROM chips fairly easily from Hobby Roms (http://www.hobbyroms.com) or some other ROM burning service. You can also burn the ROM chips yourself if you have the equipment.

Hope that helps. Thank you for your questions and good luck with your repair.