After reading through this thread, I have a few suggestions you could try.
1)I don't feel that you can not proceed until you have run MCACC and it has completed successfully. Does a sound come from each speaker including sub or does it stop on a certain speaker?
2) I would use a dvd player to troubleshoot sound output since they will all be at least 5.1. The dvr may or may not be outputting a 5.1 signal depending on content (ie comerrcials ) .BTW you dvr is a Motorola dcx3500m rebranded by Comcast.This
is the manual for your dvr , see page 29 to access the advanced audio settings.
3)If the receiver is used , I would try resetting it to factory defaults. See page 74 of the user manual.