I did some simple mods to make disc swapping easier (tape down one lid sensor and replace the other with a switch), and I tested it several times as I was reassembling it. It worked fine until the last test when I was about to put the top back on. Suddenly the disc drive doesn't work at all. Motor doesn't spin, laser doesn't light up or move. I tested all the fuses I could find, checked the connection on the switch, examined the mechanisms and cables, everything looks fine. What else could be wrong? Is it possible to test the RS2004FS chip?