Changed starter now no spark from one coil

Changed starter in my son's car. Started up, its running on 2 cylinders, spark on one coil, not the other. Catalytic converter got really hot b4 he got home, 3-4 miles.

When taking pos battery cable loose b4 changing the starter I let the wrench drop down and touch the neg post and it sparked a little. Also during starter job we broke off a little clip that was attached to a metal piece that had a wire grounded under it also that was attached to oil dipstick and then to engine block, this little box is located directly behind the fan. The little metal flat piece that cracked off held a square connector box of some kind with word "Omron" on it (resistor, relay, or something?) anyway we checked coils and no spark on 1-4 but 2-3 okay. Put new coil there and still no spark on it.

Is there a way to check the ignition module? Could sparking the batt mess up one side of ignition module? Keys were not in car at time so it wasn't turned on.

The little piece that we broke off, when I loosened the screw that held it down and the other wire that was attached there wasn't grounded good the car would do nothing when turning the key on. Could be something not grounded good cause one coil to not work?

tk

Go to autozone website and sign up. They have repair manuals online that will help .