I've read that it's because the bootloader is locked so I won't be able to flash the whole image. But if I unlock the bootloader, won't that wipe all my data? I would like to to see if sideloading can fix my issues (freezing, bootlooping) before going nuclear.
After the package is verified it returns:
E: footer is wrong
Update package verification took 0.1s (result 1).
E: Signature verification failed
E: error 21
Install from ADB completed with status 2
Installation aborted