Re-installed engine, had braided ground strap left over, can't find where it goes. I think it has something to do with the computer, as both batteries are connected and charged up, but nothing powers up.

2005 ford 6.0 will not excelerate

Braided ground strap normally goes from the engine block to a mounting bolt (likely 8 mm) on the firewall on Fords. The PCM's grounding wire is usually mounted here also.