Problems with magic 2 v5 us install

I did the first 6 flawlessly, no problems with them what so ever but im really confused with this last one; gone through with a circuit tester and no shorts have been picked up between pins and i have no cold solder joints, have checked the ps2 and the chip wiring twice, put the machine back together turn on the power supply light goes red and nothing else cant get the tray to eject or have the system even power on, is this just somethin simple that i have missed or did i really fudge up? thx in advance for any help given