It was actually on taxi-in, not push-back. I heard that they're pinning it on the 2 marshallers (one just took off never to be seen again and the other refused a drug test) but I bet the FO feels kind of bad because he probably could have seen that the GPU was in the safety diamond.
Good luck with that. PDT still fly "Queen of the fleet" - 906 HA. Everytime 906 HA takes off, it breaks the record. last time I check, it has over 72,000 cycles on it. Any fellow P*monster can testify on that.
My guess is they square the blame on the power cart for being there in the first place. stupid carts. You cant be expected to worry about a little 2 ton metal box there when they are painting diamonds(!) on the ground. why do airports always distract us like that?