I have the installers manual in PDF format, in case the customer has lost the manual/CD that comes with the projector. From page 35 of the installation manual for the VPH-D50Q:
1) Fresh Batteries?
2) Physically connect the remote to the projector witht the supplied remote cable. OPTIONAL, but may need to be done depending on environment.
3) Make sure the COMMAND ON/OFF switch on the remote control is set to ON.
4) Turn on the MAIN POWER switch on the projector, and the press the ON key on the remote control.
5) Open the panel cover of the adjustment keys
6) Press the keys in the following order: ENTER, ENTER, UP ARROW, DOWN ARROW, ENTER
7) The question about entering service mode should pop up.
8) When done, make sure you set the remote back to user mode by pressing ENTER, ENTER, UP ARROW, DOWN ARROW, ENTER. Then answer the question about returning to user mode.