Loose or cracked spark plug wire, arcing makes metallic click noise
Loose rocker or collapsed lifter on that side, need to pull valve cover to check it.
Lifter may expand after engine is running and oil pressure is up.
You have to pull off the wires for the Crank Position(CKP) sensor when moving the main wiring harness to do the heads.
CKP sensor is on the front of engine down by crank pulley, about 10:00 position
Check that it got plugged back in.
CKP sensor is the "Big Kahuna" of sensors, it tells computer that crank is turning so to "start spark and fuel injectors".
No CKP = No start
Spark plug wiring on coil pack should be:
3 4
2 6
1 5
Front
The 5, 6, 4 side gets me every time
For some reason I never screw up the 1, 2, 3, side, lol