Quick answer: It's normal for a red triangle symbol to appear on the instrument panel when the brakes are applied, indicating that the brake power cut-off function is working properly.
Friends who have just bought Boyueda S5-11 electric scooter will find that when braking, the instrument will show an orange triangle flashing and an error message E-04. You may ask, is this normal?

Don't worry. On the contrary, if E04 appears when braking, it is a normal phenomenon, indicating that the power-off brake function is normal, that is, when the owner squeezes the brake handle tightly, the motor will stop supplying power, help the electric vehicle brake, reduce the speed, and let the owner stop smoothly. This design makes riding safer.