V2 ECU is pretty old and a lot has changed.

The general procedure for recalibrating the temp probe is to hold the Select Menu button down while powering up the ECU (turn Rx on) and continue to hold until you see the Calibrate Temperature message and then release. After that the Temperature should read about 21 degrees.

The wires to the multiplex connector at the engine only carry power, not data. The fact that a broken pin was found with a burn spot coupled to smoke seen from the ECU leaves the odds very low that you have a working ECU at this point. Something shorted, and, while its possible that only power control to the engine is affected, likely you will not be able to use the engine. Just push and hold the Ignition button and see if the engine spins. If not, you're probably done.

What kind of battery was being used to power the ECU??