It's most likely the ignition.
On those cheap scooters they use those cheap white 2 or 3pin connectors.
I've seen some people use zip ties or even hot melt glue to keep them plugged into each other.
Something I could think of is the brake wires shorting out but that wouldn't cause a beep, would it?
You could also try opening the whole handlebar mask and turn left with the ignition turned on. To see if anything stands out.
But there aren't even that many wires anyways. Like: Headlights,Indicators,horn,ignition and speedometer. So it shouldn't be that hard to find some unplugged or damaged wires.