Moped just turned off while driving?

Hello, I really am a bit of an unlucky person. I think I bought a scooter today on eBay, a Taizhou Zhongneng ZN50QT-8E. I test drove it briefly, everything was fine and the seller said it had been serviced, new spark plugs etc., everything was great. Then on the way home, completely unexpectedly, it switched off and smelled really burnt and it was registered to 25 km/h but was doing 50. The NICE man said that it could be easily converted. I called him and said the scooter didn't run. He came over and took a look at it, said I should leave it there, gave me some money back and said he would call a friend who would take care of it. When I got home without my scooter, I got an email saying that the friend wouldn't be back until next week and that he wished me luck. I, the woman, was totally stunned and too trusting. My scooter is now parked 10 km away and I have to figure out how to get it out of there and what's going on with it and how I can legally convert it to a 50 km/h engine. Does anyone have any idea why it went out?