Crank no start and radiator fan stays on after rear O2 replacement

What is your question?

I forgot to disconnect battery. For ease of removal, I cut all 4 wires to the rear O2 sensor. Immediately after cutting wires, the radiator fan came on, won't go off unless ignition is off. Oh yeah, key was in on position as well when I cut wires to the rear O2 sensor. I replaced 02, and now, in addition to the fan staying on, I have a crank no start. I checked all fuses, and found them good. I tried to start vehicle with supplemental fuel, and no start. I'm thinking I damaged the ECU?? What do you think it is? Also, I disconnected battery neg for an hour, didn't help, and my launch scanner is unable to communicate. Before I started, vehicle ran great, and I was able to pull codes and communicate with ECU. I had code, and live data failure of rear O2. I'm lost... Please help. Thank You

What makes this problem better or worse?

Nothing

How long has your 2002 Chevrolet Prizm had this problem?

Just now