I've had a couple of Dells (have one now) and they can be a bit tricky to open up. The original instruction book should have directions in it. As several folks have said, open it and check all of the physical connections before you call...otherwise they will have you doing it while they are on the phone.

By the way, Dell has gone offshore...to India...for much of their technical support. I called them about 3 weeks ago (several times) and spoke to at least two techs who may have been completely knowledgable but their version of English was enough different from mine that we couldn't understand each other.