Draginol, that is a real bummer and I feel for you, loss of bees makes us feel terrible. I would be curious how these bees were closed up for transit. They need ventilation, no doubt. What was used to close them up? I think that they got too wet from condensation, not overheating or chilling. Do as another suggested, give the brood to another colony, this brood may still be OK.
When I made my nucs when they were getting ready for transport this is what I did. Was something similar done to your nucs (for ventiliation purposes).
I got a piece of hardware cloth and pushed it into the opening at the bottom front, allows for lots of air movement into the colony and the slot on the inner cover had a tiny piece of the hardware cloth put in it too. This provides fresh air to move in the bottom and the release of any moisture from the bees to be released out the top. Define how your nucs were closed up. Hoping you are feeling a little bit better today, it is a hard thing of these losses, I know. Have the best of a great day, Cindi