My friend's Xbox 360 Elite recently got the dreaded "Can't open tray" error. Unfortunately, he tried to manually remove the disk (incorrectly, but what can I say?), and the tray both came off-track AND managed to damage the tray motor. It was very clear that the drive was toast. He called me, asking me to repair his beloved Xbox. He would cover the consumable parts (in this case, just the DVD drive) and compensate me for my time.
The physical deconstruction of the Xbox went astoundingly well. Once you have the trim pieces off, it was only a total of like, 10 screws before I had access to the drive's daughter board. After nearly bricking the new drive while programming it to work with the Xbox (see "My Advice"), re-assembly was a breeze. I was even able to give it a nice air-blasting with an air compressor.
First of all, ignore the warning about the DVD drives not being swappable. The issue is that you need to replace the drive with an IDENTICAL drive (make, model, AND firmware version all have to be the same), and you need some special hardware (specific SATA PCI card, Southbridge chip, and/or USB debugging tool, plus a modified power cable). To top it all off, you need special software to dump the original DVD drive's encryption key (The drives use encryption! How about that.) and inject it into the new drive. The software and tools themselves are legal (as is what you're doing), but they can be used to do some seriously shady things.
TL;DR: Brush up on yer' seafarin' man's English, ya' landlubber.