how I got my vaio working was while laptop is turned off, press assist button, keep pressed for a few seconds, next to power, and a recovery mode is there, just restart windows mine is windows 8.1 though
The exact same thing happened on my Sony Vaio. I managed to resolve it by taking out the battery and then continuously holding down the "SHIFT" and "F8" keys then pressing Start. I have no idea why it worked, but it did!
well, worked this temporarily, but did not solve the problem permanently. after weeks or two, it again showing the same black out screen on my sony vaio. I dont know this happen because I disabled the upgradation of both sony vaio and windows, but I am facing this problem again....
Sony Officials must look into this problem very seriously, lest I am thinking of scraping this machine