HyperOS 4 Installation Guide
Happy Singh- Download the tornado_OS4.0.0.3.XPSCNXM.zip
2. Install TWRP - https://github.com/heppysingh/twrp_tornado/releases
3. Flash the zip in twrp
4. Wipe data , metadata, cache, dalvik and do a factory reset
Note : Don't wipe data before flash otherwise it won't get installed