I agree, could be one of many simple problems. I would definately look into the problem before getting rid of it. It could be cheap or even free to fix. First thing you need to find out is if the battery is dead, and if so what caused it to die. Does the machine have a backup pull starter? If so, will it start using that?
That being said, depending on how much it would cost to fix it, you might consider getting rid of it and getting a newer machine, it does sound like the problems are snoballing on you. Sounds like you have more into the quad than what it is worth. Either way, good luck.
Yours truly, sincerelly, love always, Josh aka The DirtDemon.