"RoyalLin.ux" is the same size as the "Linux" file so im wondering if it was just a renaming job and those files are just there to be backward compatible.
Maybe if RoyalLin.ux doesn't check sig files because it's just used during bootup/keycheck, then copying RoyalLin.ux to Linux might be a way around the sig checking on the current versions, it might not run 100% normally depending on what the small differences are, but it might allow us to get as far as messing with hdparm or rc.sh, just to get some information.
So if the "51" is a controller for the headunit, and
the ARM controller is the main one, then is there yet another one for the initial bootup/keycheck/firmware update routines?