there are indeed newer files from update/system installed (where did i get that the usb flash drive is not updated, maybe it was in 5.0 i used before 6.1?)   root of 1st partition GRUB_VER   root of 2nd partition checksum.syno grub_cksum.syno rd.gz zImage   so when you have to recreate the usb flash drive you would at least have to restore the files from the patchlevel you had installed like 6.1.3 update 8 or 6.1.4 (without update) - have no