DB85FL: BIOS has detected unsuccessful POST attempt(s). Possible....

Dear All,

History: System was fine with windows 7, 64 bit until I have installed windows 10 tech preview....I have installed via usb device....during installation, somehow My HDD partitions have been converted into GPT...somehow I didn't like windows 10 because of some games not being installed, so I wanted to install windows 7.  The problem started from here.

I have presently wireless keyboard and mouse.

Now when I power on I get this message:

After Pressing Y I get F2/F6/ctrl+2 options but none of them is working....I don't know whether my keyboard is working or not....so I put usb keyboard....but same problem.....system restarts restarts and restarts....