Before you start, here is a chart of what all the wires on the controller are for, as well as all the tools you’ll need to do the job.
The controller for the Radmini is located behind a metal plate held by 4 screws near the bottom of the bike. Remove this to access the controller.
Unplug the 3 connections to the left, and remove the rubber grommet in the right hand corner where the motor connector goes through using a flathead screwdriver.
Carefully cut the zipties for the motor connector located about 6 inches away from the motor on the other side of the bike, and unplug the motor connector.
Pull the rubber grommet over the motor connector, and pull the motor connector through the controller box to remove the old one from the bike. The grommet will be pretty tight between the brake cable and the grommet, so if you’re having a tough time, you can loosen the cable located on the brake caliper itself with a 5mm allen key. Once that’s loose, the brake housing can be slid and you can slip the grommet over the motor connector and the bare metal cable.
Now everything is unplugged! Pull the old controller out, and plug in the new controller, using the reverse of the steps above.