HELP chick dying

we just hatched chicks in our incubator. we took them out and put them in the brooder. Everything is the same as we have had chicks before. All of the sudden there was some very loud peeping, a chick was on it's back, started thrashing, died within minutes. Now we've lost 4 total. (of 23) 

Help. what could the cause be?? Where do we start.

We took all the chicks out of the brooder and moved them into the living room in a card board box.

We have lost a total of 7 chicks in the last 1/2hr. 4 are dead and 3 are dying they were dry and appeared healthy when removed from hatcher.

Brooder was around 90 degrees. We had new pine shavings down in a new 2x6 metal trough we just got from tractor supply. Just like the ones they keep their chicks in but a little bigger. 

They were fine there for 4 hours and now this.

we removed the remaining 11 from the trough and put different bedding in the plastic bin we used several weeks ago. we also have 6 more in the hatcher and several more pips.

well i don't think it is food, bedding or water related. we just had one die in the hatcher. it was fully fluffed and we was going to take it out but then all this happened. 

incubator/hatcher and brooder are in a spare bedroom. we did have some closet cedar blocks lying on the bed. we usually keep the door for the room closed (we have 3 cats) but we were in/out of the room a dozen times tonight watching chicks hatch and run around the brooder.