I have a Dell E6400 XFR that was repeatedly crashing, so I decided just to swap out the motherboard. However, it continues to load in "manufacturing mode," and I have tried many times to hit F2 (and others) to enter BIOS and it won't do it. The Dell screen shows up for a fraction of a second before going to manufacturing mode.
The "manufacturing mode" page says to press Fn-X to get out of the menu, but pressing that combo doesn't do anything. It also states "the setup utility will launch the Service Tag installer," but that never happens either. It eventually boots into what appears to be Safe Mode, and obviously there's not a whole lot of function because I haven't been able to set up anything.