Each DVD Drive in the Xbox 360's are "married" to the CPU. When you turn on the Xbox 360, the CPU reads the DVD Drive's Firmware which has it's unique key. Once you replace a drive, the key is no longer correct and valid for that system so it will not play any games and you will just get a "Play DVD". The only thing you can do is if you still have the original DVD Drive, extract the key and flash it to the new drive. I hope this helps.