I just dealt with this issue about a month ago. Couldn't hit within a foot of the target half the time and was slapping the trigger.

A few guys at the range told me to just aim at the target for 5 or 6 seconds with your finger on the trigger without shooting and then let down. Repeat this 5 or 6 times and if you can do it without squeezing the trigger try shooting the same way. If you can't repeat for about half an hour.

If you can do it now it's time to shoot. Draw and hold for a few seconds and let the pin cross the bullseye once or twice without squeezing. I did this drill two times at the range and it significantly improved my target panic. I'm back to where I was before and actually a better shot because I can squeeze the trigger instead of punching.

Now, every time I shoot I follow that same procedure of drawing and going over the bull at least once then coming back and shooting. I can actually stop myself from squeezing the trigger when I think I'm going to slap it.

Another drill is to set the trigger heavy and use your regular release like a back tension. Wrap your finger around the trigger and squeeze with your back at full draw and your hand will automatically tighten and set the trigger off without you controlling it.

I've been told by a few archers that setting the trigger light can actually make the problem worse because now you are afraid to rest your finger on the trigger and will punch it even worse.