Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2010 chevey equinox 2.4 L, no crank, no start, U0100 P0615 P1682
go back to the starter relay and test voltage from Batt -ve to term 86 -whilst cranking with relay in.
If you have anything much more than 0v you have a bad earth.