Hboot 2.16 is the special “partition layout” update (originally from the HTC One S C2 / VilleC2) that merges the /system and /data partitions into one large partition. It is required for most modern custom ROMs (Android 7.0+). Official Firmware (RUU) for Hboot 2.16 If you need to upgrade to Hboot 2.16 or return to stock with 2.16:
Here is the information and direct download links for with Hboot 2.16 . Htc One S Hboot 2.16 Download