High spirits - not power loss, just an increase in power required that wasn't available. A small compound with 18ft high walls is just made for recirculation - seems surprising that SF superheroes didn't take that into account, surely they practised on a mock-up building first!
High DA shouldn't have been a surprise either so, if the explanation put forward for the loss of the helo is true, someone didn't do their homework properly and it could have seriously compromised the whole op - imagine 18 dead or injured SEALs in the wreckage - always impressive to do the enemy's job for him.