I didn't bother to unplug this cable, just unstuck the cable from where it's taped down. You then have plenty of slack so you can tilt the logic board to access the antenna connector. Seems like a safer way to do it since some folks report they broke the socket here.
I didn't read the comment above from asle, and I had to take it back apart again and reroute the cable correctly. Read that comment carefully.
It wasn't obvious to me at first that I'd broken the antenna. A picture of the antenna that works compared with one that is broken would be useful. Fortunately I'd ordered the replacement part just in case, as suggested.
I think using extra heat on this spot may make it easier to unstick without breaking the antenna?
A diagram of what the antenna looks like, from the side, would make it clearer what to do with the pick. You are trying to detach the antenna from the glass, without ripping it off where it's screwed into the bottom of the ipad. Since you can't see what you are doing, and the antenna is quite fragile, that's tricky.
I think once you've broken one you would know better how to do it. When you slide the pick to the right you need to be sure the pick is moving above the antenna and not snagging on it in any way, and you need to be sure the antenna is completely detached from the glass, so you don't tear it when you lift the glass up.