05 rancher no start

i have a 05 rancher that wont start. it was running like crap and backfiring. i cleaned the carb and replaced the coil and i still can not get it to start. yesterday we check power to the coil with a test light and the light would not light up. i am at wits end on what to do. could it be the brain box went bad. any help would be great. thanks keith