Before you tear your bike apart, try a few things first and eliminate as many potential possibilities, my bikes never had the original ehcs so I can't tell you much about them, but as always check ALL connections for tight fit, twice, just to make sure you didn't overlook anything, if you have the thunder heart ignitiln module check if you get a light on it with the key turned, if you lost your left blinker make sure there's no short anywhere, inside the housing at the connection or anywhere wire may be exposed, a battery load test will eliminate a battery issue, the pcb boards are notorious for shorting out against the housing inside your hand control, one of the screws that hold the pcb board in place can cause it to short to ground, my Docs esc came with a plastic bolt to fix this problem, if you have a multimeter check to see if you're getting any power at the wire going to the starter or at the coil.....just a few things you can check that might get you further