Wiring diagram is available from here
http://manuals.monsterscooterparts.com/recreational/Razor/Wiring/
Do you have power at the controller? If you do then try disconnecting the brake connector going to the controller. If the bike now works then your brake switch is faulty and needs replacing.
If you do not have power at the controller then load test the batteries to confirm they are OK then trace the voltage from the battery to the controller to confirm the fuse, switch and connections are good.

Try disconnecting the brakes