Just a 'happy' update! I reflashed the BIOS with an earlier version (A08) and kaboom it worked! Now after that, I did update to B02 from windows.
Here is the story in short..
Problem: F5 will not boot to windows and prompts for a password with "Setup is access protected." message.
Solution: Reflash an older version of BIOS using Phoenix Recovery Disk.
Credit: Shuflie (one of our forum buddy) & Joseph (Technician from Motion Computing).