How do I revert to an earlier version of the firmware?

[EBA]

Hi guys,
I was asked by support to revert to an earlier version of the firmware but placing the zip file at the root of the storage and restarting does nothing. The update launcher does not sense anything. Is there a way to force update? I'm tempted to unlock the launcher and try some alrternative solutions but I think it affects warranty. Any suggestion is welcomed. I've lost 1.5 days already on doing this.

[Gustav_ASUS]

@EBA You can't revert to an earlier firmware version by placing the UL file from the support website in your root directory. That's something service will have to do for you if you don't want to touch the bootloader.