If you bought the drive, connect up to the Xbox 360 and it doesn't work, then it is damaged.
All 360's come with working drives. If your original drive that was inside your 360 was damaged, then you need to have a 256KB .bin dump (or the key) ready to be put into a new DVD drive.
You can buy 100% working drives here
http://www.consolesource.com/ecomm/catalog/Parts--Repair-orderby0-p-1-c-272.html You need to have your own .bin dump from your 1st DVD drive ready. If you originally had a Hitachi/Samsung/BenQ then get a
BenQ drive. If you originally had a LiteOn, then get a new
LiteOn drive. If they don't have LiteOn drives, then get a BenQ. That site seems to have everything in stock. Avoid buying a new Hitachi/Samsung.
So Hitachi/Samsung/BenQ original drive = New BenQ drive
LiteOn original drive = New LiteOn drive
Flash to iXtreme LT v1.1 firmware...
Oh, I forgot you don't have to. All you have to do is take out the PCB out of your 1st drive, and put it into the 2nd drive (drive manufactures must match). You are going to have to desolder/solder wires though. You should have no problem getting the key/dump from a BenQ/Samsung/Hitachi/LiteOn 74850c/83850c v1 (83850c v2/93450c takes time because you have to cut traces). The way to avoid this process entirely is by swapping PCBs with drives of the same manufacturer, then again you have to desolder/solder (it shouldn't be too hard).
So what drive your 360 orginally had in the first place? I am talking about your very 1st DVD drive manufacturer.