Originally Posted by
understatement
Does it have the original power cord or an aftermarket one? Some problems can occur with aftermarket power cords being plugged in to a surge protector they work better being plugged right into the socket.
Also if he used a cheap “new pin set” it could cause this type of problem or if they didn’t put the system back together right, the tray that holds the games has a lip that goes under the motherboard but a most of time people don’t realizes it and just slide it in on top of the motherboard causing games to not work properly or at all.
Personally if I bought it from a store I would take it back with the offending game that causes the lines and see if it does the same thing at the store if it does get them to replace it, fix it, or refund it.