Things You'll Need
Instructions
Reset your Game Boy Color by turning off the power and turning on the console. This resets your device and potentially fixes any small errors or glitches.
Examine the batteries to make sure that they are not dead. Dead batteries are one of the most common reasons that devices like the Game Boy Color don't turn on. Replace the two AA batteries according to the instructions if they have no power left.
Check the contrast knob on the side to make sure it's correctly adjusted. Your console may be set too dark or too light to display images. You need to make sure that the contrast is medium so that the display is functional.
Remove the game you currently have in your console. Insert it back into the system, but make sure that the game is completely fitted inside the console. If it is not, the game will fail to turn on.
Remove the current game and use a different game to see if the console will start. If it does, then your first game may be defective. If not, you may need to replace your console.