Bootloader unlock WITHOUT volume buttons

Is there any way to unlock the bootloader without the volume buttons? Mine have broken (even when the button circuit board has been replaced) and all programs or guides i have found ask you to do at least one action with the volume buttons.

Unfortunately i have also upgraded to 5.1.1 so no easy root options.

Stock rom (hence the need to unlock and add functionality due to the loss of hardware buttons)

Thanks!