Heres a Tutorial for those who get No cd or Open tray message or error. Philips/Lite-on I bought my 360 secondhand and when i hooked it all up i kept getting a Open tray message so i thought the drive may be dead so i ordered a new drive, while i was waiting for the drive to arrive i decided to search on the internet for any infomation on the error i was getting and come across people talking about POT Calibration on a forum. POT Calibration adjusts one of two lasers inside the cd rom drive heres how to do it: Tools needed: Special Xbox opening tool Xbox Screw driver Small screwdriver Multimeter Marking pen 1. Open tray then switch off xbox from the wall socket. 2. Use your special opening tool to remove plastic sides then unlock bottom case. 3. Use the screwdriver to remove all visable screws untill top case comes apart and you can see inside. 4. Now detach both cables from the back of the drive and then remove the drive. 5. Use the small screwdriver to remove the cd rom screws so that the top & bottom covers come apart. 6. Now turn the drive around so you are looking behind the laser, now you should see two small screws left and right, the left is DVD and the right is CD. 7. Now get the small screwdriver and place it in the screw now get the marking pen and put a mark at the bottom of the screwdriver so you know thats the default screw position. 8. Grab the multimeter and set it to 20ohms and place to red meter stick on the bottom of the screw & place the black stick somewhere else on the same screw it doesnt really matter where to get a reading then write it down & use your screwdriver to turn left a faction at a time. 9. With each turn stop and put the cd rom covers back on, power the xbox and try a game to see if it work, if it doesnt keep trying adjusting the screw untill it does. Good luck If it doesnt work even after all that then the drive may be dead so you need to order a new drive online.