Ok, so I'm lookin for some help
We just swapped the drivetrain out of one car and put it into another.
The car used to start just fine, Turn the key, start right up

The car we put everything into was an automatic, so we also did the 5spd swap. We just unplugged the ECU, fed it through the firewall, un bolted the sub frame and moved it all as one piece.
We also had to swap ignitions because we didn't have the key for the shell.

We go to start it and the relays just click. In the run position, the fuel pump primes. There is a hum for the engine bay that I can't identify. You turn the key to start and the relays just click. Almost like a dead battery.
We charged the battery. no change. We hooked up the charger. no change.

The shell had an alarm, but we've pulled it all out... at least, from what I can tell, its been pulled out. I don't have any clue when it comes to that stuff. Think we missed something?

Wiring problem?
We swapped out the ECUs. Is there still wiring that needs done?
Its been a while since I've done a swap so I can't remember.

Anything else I should look into?

I'm about to go "Hot wire" the starter and see if it will start that way.
Think the ignition might have died in the process of removal/install?

thanks for the help