My advice is to get that piece of junk running and sell it to some unsuspecting sucker asap. There is a reason those bikes are so cheap, they're complete garbage. My opinion as a mechanic is that your voltage regulator/rectifier (vrr) took a big ole Korean Kimchee dump on you and may have cooked off whatever playskool 'my first ecu' computer that thing came with. Do the gauges and stuff still function normally? Do you have a volts/ohms meter? With the bike running, check the voltage across the battery terminals, should be at least 12 idling, maybe 14 at 5k rpm. If that checks out, your battery is toast. If you don't have the prescribed voltage, either your vrr or your stator is roached.