Don't be so quick to blame the teenager - the fault could very well lie with Infocus and their lack of QC. I had the exact same thing happen with my 4805. One day, I aim the remote and nothing happens. I replace the remote's batteries and my 4805, which is still firmly mounted to the ceiling and hasn't suffered a fall, abuse, etc..., is simply dead. Infocus eventually fixed it under warranty but I never found out specifically what was wrong with it. I also had a bulb blow at around 1200 hours (mostly on econ. mode, with most hours racked up in 4+ hour blocks) and a month ago I started getting the colored banding from a bad light tube, plus my fan began shrieking like a circular saw, so back it went to Infocus. That $170 I paid for an extended warranty on this unit (includes bulb replacement) sure was money well spent.
I'm moving to a new house this summer and my 4805 is going to stay in the old house as a highlighted sales feature. I won't be replacing it with another Infocus projector, either (maybe Benq W500).