[_Alvaro_]

Muchas gracias por el aporte, te he visto buscar y buscar y parece que lo has conseguido por fin

Te dejo un apunte de HTCdev:

 Cita:

Step 14

To re-lock your bootloader, in the command prompt, type: fastboot oem lock.

Note: This will not restore the factory default lock, but will simply re-lock the bootloader so no further changes can be made. Furthermore, if you want to unlock your bootloader again, simply repeat step 12 with your original unlock key file to unlock your phone again.

Es posible que volviendo a bloquearlo cuele en garantia, todo dependerá del fallo que presente..