Xiaomi M365 Edition Owner's Manual page 13

Unplug the tail light connector and remove the rubber grommet. This will
allow both LED cables to go inside the battery's compartment.
Run both cables on the gap between the battery pack and the scooter's
frame, and leave them loose where the ECU unit will be mounted (see
page 6).
The original rubber grommet won't house the extra cables. By the end of
the installation, in order to seal the hole against water and dust, we
recommend the use of silicone.