Does the computer tell the starter to disengage or something? It keeps spinning but just disengages from the engine. I don't think the battery or voltage is the problem, because I can hold it in the start position and it'll keep going, just off the gear.

 

no, the solenoid ingauges the starter. if the battery is not up to charge it can spin but not have power for the solenoid to push the starter gears out to engage with the flywheel.