There could be a few reasons why it's not opening - first, the DVD drive itself could be faulty. Maybe it's a power- or motor-related issue, and it won't work until it's fixed. Another option is that ...

I started playing GTAV the other day, but couldn't enjoy the game because all of the subtleties of the game audio were lost to the noise of the "jet-engine" powered DVD drive in my first-gen Xbox 360.