Well today i tried starting my 400ex today and i hit the button and let go and the start kept on rolling and then i shut the key and the switch off and it still kept doing it. Does anyone know what it possibly could be? anything will be great thanks guys justin

Starter solinoid welded itself shut. Replace it.

Starter solinods take current directly from the battery and apply it to the starter via a set of contacts. If the contacts stick or the spring fails to open the contacts, the starter will run until the battery is disconnected, batt dies or starter dies. Starter would probably die first as they have a pretty low duty cycle.

Thanks for the information noble