Do you not offer water in the brooder right from the start? I move chicks into the brooder on the day after they hatch, and dip their beaks into the water as I transfer them in, and do this 3-4 times that day till I see them drinking on their own, then offer feed.
Also, does the heat lamp provide enough heated area for the number of chicks? Did they pile up on top of each other trying to reach the warm spot and smother some on the bottom? Consider a second lamp or an electric hen if this is the case. E-hens are much better on the electric bill btw.
Sorry to hear this sad news. I just lost 3 chicks in my hatcher, one fail to break out, one fail to pip, one late mortality. Very frustrating trying to sort out these problems. Better luck with the next group. I hope the other little one pulls through.