a loose battery terminal doesn't have error codes, goes to show poor quality and service from the dealer....
its a lexmoto so the list of possibility is almost endless just to say on a forum, get the dealer you bought it from to collect and fix as its their sale and their problem- thats the rant over with....
not very familiar with that bike but most likely its more electrical based, a sensor fail or error, which one exactly without interrogating the ecu is trial and error.
one thing to see is if you pull the clutch in and move the bike forward or backwards 6-12inchs and try starting again with the clutch pulled in, if not move the bike with the clutch out and try with clutch in to see if you get any joy.
after that it is literally checking every fuse block, connector block and wiring, undo, inspect the pins and reconnect). it might just narrow things down.