Use edge TWRP Step：
1,Please get the khadas-edge-pie SDK and setup the build environment.
2,Back up the default recovery, the directory path is bootable/recovery, so that you can restore the recovery at any time to provide the full SDK.
$mv bootable/recovery ../
3,Delete the default original recovery
$rm -rf bootable/recovery
4,cp TWRP source
$cp -rf xx/recovery_edge_TWRP bootable/recovery
5, Compilation, Clearing the previously compiled content, because the files in the out directory that have been generated conflict with TWRP, will cause TWRP compilation to fail.(make clean)
or you can restore the previously compiled content
$mv out ../ $source build/envsetup.sh $lunch rk3399-userdebug $make recoveryimage -j36
6, Upgrade the compiled recovery.img separately (out/target/product/rk3399/recovery.img)
7, After upgrading, enter the system and execute the following command:
$adb reboot recovery