Here’s BIOS update for Lenovo Z710 notebook just from official Lenovo servers. One of users gave me link after mine crying in this post on Lenovo forums. I’d problem with bad mapping on F4 key on 7FCN35WW BIOS version, after updating to 7FCN90WW version (from link above) problem was solved. Just flash it on Windows and feel happy without contacting service. I still don’t know why update is not published on official site.
Update 23-june-2014: Lenovo just released 7FCN95WW BIOS version and it officialy may be downloaded here, finally!