After the BHA has been pumped down, some guns may fire without any problems, but at some point there could be a communication interference that prevents further guns from firing. After adjustments are made to try to restore the gun to firing order without success, the BHA should be pulled out of hole to inspect.
After pulling the BHA, and disarming the guns, it should be inspected to find the cause of the error. In this case, after disassembling the cable head, it is found that there is hole burned in the protective rubber boot that covers the K20 pin in the cable head. After removing the boot, it appears that the conductor is burned.
If rehead procedures have been followed correctly, this issue is extremely unlikely and the only appropriate action would be to contact the cable head manufacturer. Crews should be reminded of proper rehead procedures.