VG-C4EM battery grip

[gplawhorn]

I bought a used A7RIV from eBay. It was very new, very low frame count, and in fantastic condition. However, it won't work with the Sony camera grip. I tried two different brand new grips, and neither worked. I talked to Sony support, they could only suggest returning the grip. I inserted the grip as the manual showed. A half press on the shutter would focus, but it wouldn't release the shutter. None of the buttons on the grip would work, either. The camera buttons worked properly when the grip was attached. I tried resetting the camera.

Any suggestions? Is there a special "make it work" setting I'm missing?