1. Download firmware and unpack.
2. Copy the folder know as script to your TF card.
3. Power down the device.
4. Slot in the TF Card and power on the device.
5. The screen will start and it show Updating the Android OS.
6. Wait until the process complete. It will ask you to remove the TF card.
7. Remove the TF card and the device will power off automatically.
8. Use your computer to delete the script folder inside the TF card.
9. Power back the Apad. You are done .
Where to obtain the firmware? Please refer to the manufacturer. Please use the proper firmware, which if a wrong firmware, it might damage your device.
Try this at your own risk. I will not be responsible for any damage that causing by above step.
and i can't guarantee it work for all Apad.