The error code 25 means that the sensor in the brake lever is misaligned and needs adjustment. This also happens if the levers are applied when turning on the bike.

It is either an adjustment issue, or the possibility that one of the rare-earth magnets in the lever got dislodged during a ride or during shipping.

You can find out which is causing the error code by unplugging the brake sensor connections individually.
-Please realign the arrows on the plug before plugging them back in.

Once you have established if it is the left or right lever, you would loosen the 2.5mm (RED arrow) grub screw (that holds the 8mm nut in place), and make small adjustments to the 8mm nut that holds/moves the sensor into place.

Test multiple times, until you've figured out the proper adjustment point for the sensor by either loosening or tightening the 8mm (BLUE circle) nut gradually.
-Apply and release (actuate) the brake levers between adjustments and restart the bike.
The error code should clear when the sensor is aligned and bike is restarted.