I would try:

1)Make sure there is no bent pins in any connectors. I feel your stress...but make sure you reconnect your connectors gently.
2)Check to see the harness from the radio to the changer is good. Get a multi meter, one long solid core wire, and a friend. Disconnect the cable from both units, place the solid core wire into one female hole then run the other end to a multimeter, then find the matching male pin and place the test lead on that pin. if you have continuity...it is not open. Check all pins. The reason why you use a second person is that person can sit in the front seat and use the wire to check one end of the harness while you sit in the trunk w/ the multimeter checking the other end.
3)You could also try disconnecting the harness off the back of the radio head, then pull the neg battery cable off the battery(make sure you know your radio code), wait a few minutes, connect the changer harness back on the radio head, THEN reconnect the battery, enter your code, then see if the changer works.
Good luck!