The only thing in the cluster that will keep your car from starting is the PATS system, this module is in the cluster and is responsible for reading the chip in the key. First thing try a different key if you have spares, if not contact a locksmith to cut you some and program them. You do not have to go to the dealer for programing and if you have to good keys you can program your own additional spare keys. I have seen these systems stop recognizing a key or all the keys, a relearn of the keys usually fixes this and most locksmith have the
scanner to do this. $4000 to fix a cluster WTF try circuit board medic they went through my 05 cluster for $170. A quick note if you swap clusters, say you find a used one, the keys will have to be reprogrammed to that cluster. I put a spare cluster in mine while the original was being worked on, when the original came back it had to be reprogrammed again.