On the side of the projector closest to the buttons for the projector, there will be some screws in between the grills for the fan intake/outtake. Unscrew these and these will allow you to slide/lift off the top of the projector, the section that has the buttons on. Underneath here is where the projector bulb is.
On these models the projector bulb is in a different place, so it’s annoying if you’ve not replaced the bulb on these models before. Usually there is just a section underneath that you just unscrew and the bulb is there.
To reset the hours, it’s normally always the same for the BenQ projectors. Open up the On-Screen Display (OSD), go to System setup – advanced – lamp settings – select Reset Lamp Timer.