Without actually having the car in front of me....it might be a bit harder to help....

Possibly the wire inside the enclosure came loose?
If you have glass AGU fuses, somethimes they "look" good, but actually will not pass current. The element has lost contact with the end....which you cannot see.
You could try swithching the RCAs from the front amp to the sub amp, just to verify the RCA is good.

just a few ideas.....