|"Recently my CPU and GPU were overheating horribly"|
What were the temp readings?
"Removed my HDD, GPU and mobo to clean all my fans out etc"
Why on earth would you do all that? All you needed to do was give the heatsinks a shot of compressed air to blow out the dust bunnies. Did you remove the heatsink from the CPU to clean it? If you did, are you sure you reinstalled it correctly? You didn't bother to list your system specs so you'll find your CPU on the following link & check the thermal paste application instructions. If you applied paste any differently than is shown, you did it wrong:
As for your video card, it's a GTX 250 (not 250 GTX) & requires a minimum power supply of 450W. It also requires a 6-pin or 8-pin PCIe plug, did you reconnect it? You didn't remove any parts from the card, did you?
"both buttons work but the LED's don't?"
The power & reset button do NOT have polarity but LEDs do. You most likely have them plugged in backwards.