how to DOWNGRADE Hikvision Cameras

hi guys, I need your help, I want to DOWNGRADE my 2 cameras, , so please help me to DOWNGRADE to this version IPC_R6_EN_STD_5.4.3_160902 ,.

I already tried to Downgrade, but it is now Downgrading in my Cameras.

Please help me to DOWNGRADE my 2 Cameras
-[2.8mm] Hikvision DS-2CD2542FWD-IWS 4MP Built-in Mic Wifi indoor Dome Camera
&
-Hikvision DS-2CD2442FWD-IW 4MP Built-in Microphone Wi-Fi IP Network Camera POE

Currently I am having this file in my cameras...

how to DOWNGRADE Hikvision Cameras