My SWFT electric scooter doesn't turn on. I bought a new charger and i

You can open it up and get to the battery. Using a voltmeter on the battery will tell you a lot about the problem. If the battery shows nominal voltage, then disconnect it and switch to ohmmeter to trace the wires for an open.

If the charger is good, plugging it in should allow it to turn on. Obviously, you can't ride it that way, but that would indicate an open circuit or a control component failure.