The lamp housing is usually a small square door that you should be able to access by removing 4-or-less screws. Here's a picture of one of the DLP units:
Usually removing the lamp and reseating it (pushing it back in and tightening the screw in the lamp housing) will fix many issues with DLP where the unit can't turn on.
Does that help?
Please help me get my lamp out and check the on/off switch on my 3 year old HL85679w 56 in Samsung TV. I have read numerous threads about taking the door off and how eeeeasy it is to access your lamp and switch. Well I have taken the entire wrap around back off and it does not look anything like the other pictures of other models I have seen! The TV shut off in the middle of a show without warning and will not power back up. When I hit the power button I get two clicks like it turns on and immediately back off. So any advice there too. But PLEASE>>>>how do I get to the lamp/switch on this model!!