@giuseppe: Forget the bootloader. Boot up from a live cd distro, then from within that use a text editor and open up the /etc/wfe/conf/settings file on the Astaro. Change reset_pwd = 0 to reset_pwd = 1 and save. Now remove the live cd and reboot. Astaro will provide you the option to change your password once it loads.
@giuseppe: Forget the bootloader. Boot up from a live cd distro, then from within that use a text editor and open up the /etc/wfe/conf/settings file on the Astaro. Change reset_pwd = 0 to reset_pwd = 1 and save. Now remove the live cd and reboot. Astaro will provide you the option to change your password once it loads.