I have one theory that doesn't involve your hens simply hating him - and that is he could have boinked or been hurt otherwise before the original attack. At the sight of blood, quail just can't stop pecking at it and this could have caused his condition when you found him. When you reintroduced him later, he probably wasn't sufficiently healed to stop the behavior and they might also have seen him as an invader of their territory as you separated him (for how long?).
What I would try, is keeping him alone where they can see each other until he is fully healed - not a sign left of the pecking.
If you have a different cage you can place all the females in, where you can place him right next to them, that would be best.
Once he is fully healed, you can then attempt reintroduction in the original cage - it will become 'new' territory to the quail if they've been away from it for 1-2 weeks and this will reduce the risk of fighting. If it's absolutely not possible to keep them in a different cage, I might place all the hens in the rabbit cage inside the coop and allow him to roam freely in the enclosure. That way it will become his territory which might reduce the risk of the hens attacking him when reintroduced, but potentially it could also cause him to be overly aggressive with them which might again cause them to become aggressive with him, so it really is preferable to have them all in a different cage for a while. But if you have to keep them in the coop, you can rearrange it before releasing the hens - add a pile of hay, a log, spruce branches to hide behind (do they have hiding places now?), place and boxes, feeders and water differently - that will make it seem new to all of them.
One last strategy I've read about on this forum, is giving them treats when doing the introductions. Give them some bugs, seeds, grass clippings, pumpkin, whatever you know they love, to distract them. Once done eating, they might have forgotten what just happened.
I have never had coturnix (assume that's what you have) but I do have button quail and once I spooked them and caused a young roo to boink. His siblings started pecking at the blood right away. In his case, all I did was placing a birdcage (with the bottom removed) on top of him for a couple of weeks, till the area looked normal to me. When I removed the cage, there were no issues at all, he blended right back into the flock (both males and females, probably 10-15 birds). But I'd be a bit more careful in your case.