La recovery stock è backuppabile così :
1. Root your phone, which can be done by towel root or by just booting a recovery like he said,
fastboot boot twrporwhatever.img, then flash supersu
2. Boot phone that has stock recovery
3. adb shell
4. su "watch your phone to grant root adb access if you haven't ever done it"
5. dd if=/dev/block/mmcblk0p43 of=/sdcard/recovery.img
6. This will put flashable recovery.img on your internal sd card. Copy this and save it for later
7. "fastboot flash recovery recovery.img" will get you back to stock recovery, "fastboot flash recovery twrporwhatever.img" to flash custom recovery.
O sbaglio?