TWRP is a custom recovery, don't flash it to the book partition.noob question to flash twrp on my european model do i have to use fastboot command: fastboot flash boot twrp.img ?? and then i can flash cleanstate kernel from external sd? i shouldnt loose data.. right?
Fastboot flash recovery.img.
Unlocking the bootloader wipes the internal storage, if your bootloader is unlocked already, you won't lose anything. Cleanslate kernel has to be flashed from SD card.