So I'm a little lost here. I dealt with Mr. Burke in Megaton and declined his offer due to the fact that I wanted to raid Megaton (and it's people) for all that I could before blowing it up. Well now I can't find him at all. I don't have a high enough lockpick value to pick the lock to his house and he is not with Tenpenny (even though Tenpenny mentions him). Anyone know where I can find him so that I can accpet his offer? If I can't find him and still blow up Megaton, will I still get the apartment at Tenpenny Tower?

You can't find him. You only get one chance to blow Megaton and if you decline to do so he is removed from the game