Tacoma 3.4 Wont Start after Motor Swap Any Techs?

So it began with my buddys 02 Tacoma 2.7 Auto Prerunner. He did a motor swap to a 02 Tundra 3.4 V6 motor and changed the transmission too. Also got a 3.4 engine wiring harness and computer, but still left the 4 cylinder oem fuse box assembly and dash wiring. Over the past few months we have been doing the swap. And just today we finally came to try to start the motor,connected the battery that he was using before charged it and it had more than 12.6 Volts. So good there, then got some new , somewhat kinda cheap quality battery terminals that got me thinking they may be a problem. So we turn the motor and no power to nothing at all. But we noticed we missed a cabled from the fuse block from the battery so we connected that and finally got power to the truck but when we crank it over the starter wont click or nothing . You can just hear the relay click. And there is 12Volts to the starter. What makes it strange is when you crank to start it wont do anything but the light on the interior clock dims down all the way dark, like if its enough power. Or skeptical its wiring or the cheap terminals, or not enough battery power?

 

Ooops, deleted. Just noticed in title ... I'm not a tech.

 

Or suggestions? Anything really.

 

Try jump starting it from a running vehicle, charge the battery and make sure all grounds are attached.

 

Those terminals sound a bit suspect. I've seen vehicles including my Taco, Nissan Maxima and Ford Explorer act strange when a battery terminal has a weak connection or a loose wire. Starters need super high amperage to work so I'd give all the large gauge wiring a look.

 

The main power cable to the starter from the battery has power?
Are you getting power to the wire that feeds the solenoid to engage the starter?

If all your connections to the starter are getting power when you turn the key to the start position than check your grounds.

Hope there was no release of magic smoke that wires need to function