Can’t get 1968 BB to crank over

Shutudown4 here
Very frustrating past few weeks
Ready to start fresh BB
Having a major ignition wiring issue
1968 cuda
I’ve never had a single issue w this dar
Wiring is all tested and correct
Using power master starter obviously because of TTI big block pipes
Can’t get 12 volts from trunk battery up to the solenoid relay
0.0 volts. Motor is well-grounded in several areas
Ran a wire directly from battery to get the 12 bolts to relay
Turned key and only got rapid fire starter solenoid clicking
Start won’t engage to crank the motor over
Headlights won’t come on either
What am I missing?