No display after cleaning keyboard

I wish the answer was as simple as changing out the keyboard, but the keyboard ( and monitor) works fine on the second computer connected to the 'KVM. I've done a hard reset - CPU and aux fans light up and turn, but I can't be sure the computer is posting as there is nothing displayed on the screen - not even during the start-up prior to windows loading. Also this computer has never had an audible post beep. The computer was up and the screen was on whe I used the cleaning compound and it suddenly went black and has stayed that way. I think I hit a key combo that disabled video - is that possible? I appreciate the help!