hey i'm no expert on here as i just literally just joined lol, but regarding your issue, have you tried using the original win installation disk and booting that, i know you can do a repair thing with it.
also ive had it before where the startup repair just kept going and going...but then i reset it a few times more and it went back onto normal windows. this is prob isnt the case with u and im sure you've tried restarting many times. but if its a laptop maybe wait for it to completley cool down before trying again.
good luck! im sure someone far more knowledgeable will give u an answer on here