E-Bike Display Dead / Won't Power On

The display is blank and the motor gives no assistance even with a charged battery.

What causes it

A dead battery charge, a loose display connector, a tripped battery BMS, or a corroded contact after rain.

What to do

Confirm the battery is charged - check the charger LED and the pack indicator.
Remove and reinsert the battery - this resets the BMS and clears contact corrosion.
Check the display connector - the display is often the fault path; re-seat it.
Check the battery fuse - some packs have a replaceable fuse.
Clean battery contacts with contact cleaner if they look tarnished.

If it still won't start

Test the charger output with a multimeter (expect the battery's voltage) and check the battery charge port. A dead port or BMS needs professional repair - never open the pack yourself.