oh... I forgot.. Use this
link to find your ECU by the model number on the ECU case lid.
Its just strange that after installing your ECU that the fans stopped working. I would suspect the ECU main harness. You can test the pins on the thermostat harness wires and the pins at the ECU harness for continuity using the FSM pinout guide.. (Remember, all of the grounds are in the Engine compartment). I would also test continuity with the MAF harness.. But if could be just a bad replacement ECU.
Ive done alot of testing with the NX and the grounds are absolutely terrible and each location has a different quality. But I agree with you, your description dont appear to be grounding due to items being blown out! When you did the engine swap, did you install a new harness or did you splice into your old harness?