rgy, I agree with tefer, you need to know what happened in the box. This will also give you a heads up on what going on in the fourth so you can potentially work to save it.
During the winter, I use a stethoscope to listen to the hives. I had one hive with no sound and no movement at the entrance. I thought it was dead. Lifted the lid and sure enough, no movement that I could see. I wanted to know what happened and since they were dead anyway, I lifted the front of the box away from the bottom board to see if all the dead were there. Guess what, the cluster was at the bottom of the box -- they were just having a "quiet" day! Closed 'em up quick and went home. This weekend was warmer and they were flying like crazy!
The point is, you have to be sure before you write them off. Could be smaller boxes are needed or some combining is in order? I'll keep my fingers crossed for you. Good luck!