S3 - blue light on front panel and nothing else

So I just got home about an hour ago and noticed one of my S3's had no display other than the blue light. I go over to that input and there's no image or anything on screen. I pull the plug to reboot and still just a blue light. I open it up and the fan isn't spinning but the HDD is. I swap out the power supply with a spare I have from a new S3 and it's still just a blue light and nothing else. What could the issue be?