It sounds like the power from the battery pack may not be reaching the controller. This could be caused by a bad fuse, bad wire connector, damaged wire, or from a loose connection. The first thing I would do is test the fuse to make sure it is good. Here is a video guide explaining how to test electric scooter and bike fuses:
If you do not have a multimeter to test the fuse with then the fuse could be replaced with a new one to eliminate the old fuse as being the problem.
If testing or replacing the fuse does not solve the problem please let me know and we will take it from there.