I don't have specific experience with this ATV, but I have had similar issues with other motors and have learned a couple of things.
Just because the starter is turning does not mean that there is enough juice in the battery to energize the electronic ignition. You can pull the cord and get the motor spinning fast enough that the Stator will fire the ignition but a low battery will not spin the engine fast enough to do so. Most electronic engines will not start on less than 10 volts and many will not start on less than 12 volts.
To check what is going on you first need to know if you have spark while the starter is spinning. If not you need to determine why not. If the battery is good then there is a problem between there and the ignition module. You are going to have to trace your power from the battery on up the line to see where you lost power to all the stuff that quit working.