How to bypass some of the features

Question

I had this stereo installed, and different options that I was told it had were not available unless the E Brake was engaged, when I asked about it I was told for $100.00 they could bypass everything so that all the functions would work all the time. Is there any way that I can do it myself without giving them the $100.00, since they didn't mention any of that before the system was purchased and installed. Thank You.

It is a Pioneer Premier AVIC-F90BT