I still say it's ground!

Check the ground wires at each of those locations, not just the hot leads.

There is a ignition wire to the starter solenoid that if improperly connected WILL NOT START THE CAR! And it's a small wire, about 16 gauge. It's easy to hook it up the wrong way.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car