Day old chick pecking injury, help

[MichelleMC]

Hi, I have a chick hatched by a broody hen, can't exactly be sure but at very most he is two days old, more likely one day. He is the only one to have hatched out of a clutch of eggs she is still sitting on. We discovered him this morning and everything was fine, the mother seemed ok and accepting of the chick. We checked a few more times and all was ok, but this mid-afternoon I found him outside the nest box in the coop, all bloody. He had been pecked badly--thought he was dead but it turns out was still alive. His entire back and side have been pecked raw, no feathers or skin, poor little thing.

We have taken him inside and are keeping him under an Ecobrooder, and giving water with a syringe. Some very thin gruel which he doesn't seem to want and one very small dose of water with some electrolytes so far also. This evening we gave some water with a little sugar in it which he drank a good bit of. Although he drinks when we give him the syringe, he doesn't seem willing/able to go to the waterer or feeder on his own. He is chirping and alert but seems exhausted, or the injury may prevent him from moving around. We can't get him to the vet until tomorrow morning.

My question is, how often should we give him water until we get to the vet. Every few hours? I am afraid of over force-watering him as well. I am very sad over this, it's just heartbreaking. Thanks so much.