What should I do if I encounter the error "The Serial No has not been registered"?

What should I do if I encounter the error "The Serial No has not been registered"?

To resolve this issue, please follow these steps:

1. Click "Recovery" in the settings menu.
2. Connect to a network.
3. Clear the cache in the settings menu.
4. Upgrade the Android system by following this path: Settings >>> About >>> Version >>> Detect System Update >>> Check Version >>> Click Upgrade >>> Upgrade to the latest version (Ensure the device has sufficient battery power).

Applicable Models:
- CRP129 HD
- CRP919 EV
- CRP TOUCH PRO ELITE
- CRP123X Plus
- CRP123X
- CRP129X Plus
- CRP129X
- CRP909X
- CRP919X
- CRP919X BT
- CRP919X Lite