The sticky says its most likely a problem with the radio signal, though some form of internal issue is possible too. Assuming you've been over your radio and checked things like throttle trim etc, then I see other option but to send it in- no way you can repair it at home given the billion little components, any of which might need replacing. I know sending it in sucks, and will take a while, but feel free to make your friend pay for shipping- and check over his truck at the same time to see why he borked up his own esc..
