DEAD completely

Twice this week my dart went dead completely. Went to the garage to take it out and nothing. No lights, horn, four ways. I removed the battery ground strap at the engine and filed off some paint and hit the cable end. Checked battery connections and they were fine.

Today I walk in the garage and my four ways are blinking, I must have left them on last night when I had nothing and somehow it regained power. I checked the bulkhead connector and shook it, and pulled on it today while I had the four ways on and they continued to work. All the wiring is new, the bulkhead connectors were also replaced last year. Is the bulk head connector the only thing that could kill everything. I now know the ground to the engine is fine, so that eliminates that.