Teclast P20HD, N6H3 – root method

Yes, device is ROOTable but require some time

1. Recovery is not needed. You have to unlock bootloader using this metod.
2. Use Linux (ubuntu for adb/fastboot)
3. Find stock firmware, extract *.PAC file and modify boot/recovery file using MAGISK manager
4. Now it’s time to sign custom image using self-signed certificate (image and vbmeta)
   1. [Tutorial] How to create a custom signed vbmeta.img for Unisoc using AVBtool
   2. [Tutorial] How to extract public keys from a vbmeta image
   3. [Tutorial] How to use AVBtool and a private key to sign a Unisoc (SPD) image
5. If You have modified bootloader/recovery using magisk (magisk_patched.img), signed vbmeta_custom.img file using self-signed certificate, unlocked bootloader open Linux and
6. type “adb reboot fastboot”
7. start flashing two files
8. fastboot –disable-verity –disable-verification flash vbmeta vbmeta_custom.img
9. fastboot flash boot magisk_patched.img
10. Finish :)

* If you fail, start again teclast P20HD, N6H – bricked bootloader! stuck at starting screen! – muszak.eu

* I have bad experience using windows, many steps can fail without reason, so… if you fail, think about linux/ubuntu/etc.

*mirror for avbtool

*Below is my chain_partition for avbtool.py based on vbmeta-sign.img

   avbtool.py make_vbmeta_image \      
  --key my_private_key.pem \      
  --algorithm SHA256_RSA4096 \        
  --flag 2 \      
  --chain_partition boot:1:keysimg/boot_key.img \     
  --chain_partition recovery:2:keysimg/recovery_key.img \     
  --chain_partition keysimg:3:keysimg/vbmeta_system_key.img \     
  --chain_partition vbmeta_vendor:4:keysimg/vbmeta_vendor_key.img \       
  --chain_partition l_modem:5:keysimg/l_modem_key.img \       
  --chain_partition l_ldsp:6:keysimg/l_ldsp_key.img \     
  --chain_partition l_gdsp:7:keysimg/l_gdsp_key.img \     
  --chain_partition pm_sys:8:keysimg/pm_sys_key.img \     
  --chain_partition odmko:9:keysimg/odmko_key.img \       
  --chain_partition socko:10:keysimg/socko_key.img \      
  --padding_size 16384 \      
  --output vbmeta-sign-custom.img