The main reasons are as follows:
1. Insufficient battery power.
2. Faulty connections.
3. Battery not fully seated in tray.
4.lmproper turn on sequence.
5. Brakes are applied.
6. Blown discharge fuse.
You can fix the above reasons.
1. Charge the battery.
2. Clean and repair connectors.
3. Install battery correctly.
4. Turn on bike with proper sequence.
5.Disengage brakes.
6. Replace discharge fuse.