In most cases, nothing will go wrong at all, but it's important to know that there's an associated risk and not to treat the process too lightly.
It's good to have a spare copy of all important files from your PC before you start.
Follow these procedures to see if that is the problem. Get the manual for the monitor to find out what these colors mean. Swap the monitor with another if you have an extra one at home. Insert a music CD into its drive and check if you can hear audio. (For HP and Compaq computers with VISTA, use F10, For HP Pavilions with XP or earlier version of OS, use F1). This will detect any attempts to install viruses that could destroy our entire system in one second! Make sure that you place the computer in a well ventilated room to avoid overheating.
If you can hear audio, it means the computer is running ok. Find a different power supply outlet (or power strip) for the monitor and computer and try to reboot the computer again. If the LCD screen on the monitor is dead, then it's impossible to see if the computer is booting up or to what point it has booted up. Replace your monitor if it's defective or continue to Step 4 if you still have problems. To get rid of the corrupted drivers, do the following: a. Reboot the system and return to a previous stable configuration if possible d. At this point, if your computer is still under warranty, its time to call for help. BIOS - the Binary Operating System may be corrupted - Use of Safe Mode to boot system. Remember that NUM LOCK should be OFF for the arrow keys to function. If Windows launches before you can choose the safe mode, restart computer and go to step a. You can choose "Safe mode with command prompt" option if you know how to use MS-DOS e. Reset your BIOS to the default configuration following the motherboard's manual instructions. Make sure that you have replaced every item that you had removed from the chassis, close it and try to start it up h.
Remove all external peripherals (printer, cameras, scanners, etc) and connections until the computer returns to normal. If not, you can get a computer geek to come to your house (it is cheaper to take your computer to their store) or try to fix the problem yourself. Is AGP/PCI video card compatible with your operating system? Turn on the monitor and try to reboot the computer again. You can choose "Last known good configuration" to go back to the last known safe shutdown state. If you have added any drivers or corrupted any files the last time you used the computer, the safe mode will help you get back to the state before the changes, when the computer was running smoothly. BIOS - the booting software may be corrupted - Use of Recovery Console to boot system a. If none of the above works, its time to see professional help!
I would say, just go for it - some modern machines offer the ability to back up the BIOS and recover in the event of an error.
If however you don't have this option, make sure you have access to another machine so that you can download a recovery image or emergency image (different names across different manufacturers) so you can do a recovery if needed. Changing it back after flashing made Windows boot normally.
Or maybe the system has gone into power conserving mode. Power cycle the monitor (turn OFF and then ON) and wait for a minute or two to see if screen lights up. Wiggle the mouse or press ENTER on the keyboard and watch the display screen. Check the power supply to the monitor and the cables connecting the monitor to the computer. Check that there is a connection between the keyboard and the computer.