Welcome to the forums. Unplug the wire from your neutral connector and temporarily ground it to the engine and see if your neutral light will come on. I think you have two problems, because I don't think a bad CDI can cause the neutral light to not come on. But I'm guessing that your CDI might be the reason for the no spark issue. Sometimes, you can tap on a bad CDI with a screwdriver handle while trying to start the ATV and it will start working again. If not, I would try swapping the CDIs. Swapping the CDIs shouldn't cause any damage to the CDI unless there's already a problem that's causing the ATV to fry the CDI. I doubt that's the case, though.
Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.