Question: What is the little hole on the back for?
DON’T DO IT! The little hole on the back of the unit is a firmware upgrade feature… a carryover from the DPM2 product line. It will put the DPM3 into a firmware upgrade mode that is looking for a firmware.exe file, which is not available for the DPM3 devices.

Verification Source: Jackie Warren, Philips Product Specialist