The Stable update V8.5.2.0.NAJCNED has been officially released for MI 4S (codename is aqua). Before updating, please make sure you have downloaded the exact ROM matching your Xiaomi phone/tablet. In Fastboot mode, you can check model code by typing fastboot getvar product in cmd/shell.
The firmware files posted here are all official Xiaomi ROM, xiaomiROM.com do not own and never modified those firmwares，you will always download the file from Xiaomi server.
You may interest in those contents: MI 4S ROM Topics Xiaomi Devices Index
Download Mi 4s (aqua) China MIUI 8 V8.5.2.0.NAJCNED Fastboot ROM with Android 7.0. Firmware size is 1.4 GB.
Download Mi 4s (aqua) China MIUI 8 V8.5.2.0.NAJCNED Recovery ROM with Android 7.0. Firmware size is 941.0 MB.