It is unlikely that the grip had anything to do with the lockup. Did it occur repeatedly with the grip or was it a one time event? The grip shutter release is a passive switch and would not have any effect on the body's release function. There is no electronics in the grip, just switches and a multi-pin connector and a battery tray connector. The lock-up is a typical way that the camera behaves with a number of lost connections such as the lens, battery terminals or firmwear crash.