upon factory reset operation we make sure to force the PARTUUID to

"0xDEEDBEEF" under all circumstances even if no repartitioning is
necessary. This should fix cases where due to certain misconfigurations
the PARTUUID changes and thus misbehaviour might result. Thus, a factory
reset operation now also resets the PARTUUID and not only reformats
userfs. This refs https://homematic-forum.de/forum/viewtopic.php?f=65&t=62833

buildroot-external/overlay/base/etc/init.d/S04CheckFactoryReset

@@ -32,11 +32,12 @@ check_factory_reset() {
     # use resizepart to resize the /usr/local partition to the maximum size of
     # the disk
     parted -s ${DEV} resizepart ${PARTNUM} 100%
-
-    # force PARTUUID to 0xDEEDBEEF (because parted changes partuuid)
-    echo -en '\xEF\xBE\xED\xDE' | dd of=${DEV} conv=notrunc bs=1 seek=$((0x1B8)) 2>/dev/null
   fi
 
+  # force PARTUUID to 0xDEEDBEEF (because parted changes partuuid) even
+  # if no repartitioning was performed.
+  echo -en '\xEF\xBE\xED\xDE' | dd of=${DEV} conv=notrunc bs=1 seek=$((0x1B8)) 2>/dev/null
+
   # we create a clean ext4 partition now
   mkfs.ext4 -F -L userfs "${DEVNAME}"
   tune2fs -c 0 -i 0 "${DEVNAME}"