I was looking at photo #1, the grey connector to the amp board on the left as viewed from the photo looks like it is bent slightly. the same connector on the amp board on the right is perfectly perpendicular to the board... Maybe this could be part of the issue? If this is the case, it might be worth some close up's of that particular connection. Andrew or Ian would know much more about what that connection does.. Also, i would think that the other channel would work even if this wire is not making a good connection.
Also, an obvious question, did you verify that all of the other wiring connections within the amp were still securely connected? If the box had a sharp impact, one of those connections could have come loose, again unlikely but possible....
Also, is the ground nut still tight? I would assume that this is the least likely problem, as the amp would be erratic with a loose ground nut, and yours is completely dead. However, this is something that can be easily checked with the top lid off.
I would think this is a connection issue, as the likely hood of both amp channels failing in transit is almost nill, also we know the power supply is good because you get LED power indicators on all of the boards....
I hope this helps.. Good luck man, hopefully it is like i hypothesised and it's just a loose connection that is a 2 second fix.
P.S. Andrew noted the problem before i could even finish my post..... do what he said