You might make up some jumper wires with alligator clips & jump each/all connections including grounds ALL BACK TO THE BATTERY & if normal then all the hard components are good & it is a positive or negative wiring/connector/ground issue. you might remove one at a time till the issue flares which pinpoints the problem. you might have to modify this procedure to suit but you get the jist of it. we gotta do some elimination. stay in touch (we got your back).