Adam,
Picture #2 shows the origin of the short working its way into the surge protector. Note the heat deformity next to the red wire. Somewhere inside the surge protector on the load side, the red wire and the neutral got together. Seems strange under a no load condition and the green LED's all lit.
Typically when a neutral is lost under a load, either it quits working or creates a path back to ground by way of the least resistance like a PC Board. Your insurance should cover this failure.
To check for damage downstream of the failure, replace the damaged neutral wire (add a j-box if necessary), turn off all 120 circuit breakers. Turn on the 50amp main first, then 1 at a time and see what works. Hope this helps, Fred
PM me if you want to talk on the phone.