How to downgrade from one ui 7 to one ui6?

[embittu]

I am using smart switch PC app, but after downloading software of 15GB at 100%,it's saying software update mode check failed. What to do?

[Anonymous]

Usb problem most probably

[Logout123]

Download odin software.
Download firmware file
Connect to pc ,power off mobile, hold power button+vol down button to enter download mode.
Open odin on pc, and add firmware file and start.
Note[ put usb debugging on in developer option settings].
Click build number option 6-7 times in software option in settings]

[Sameer]

Take a backup and use a smart switch to downgrade