I have no idea what happened to be totally honest with you.

I got home, tried to turn on my 360 from my controller. But it wouldn't turn on, weird.. So I turned it on by hitting the power button. test drive started to load but the sound had this high pitched static. I turned off my 360 and turned it back on. This time it gave me a bottom right flashing red with an error 75. I had just flashed my samsung FW, I did some research around here and thought maybe i just needed to screw everything back in. Tried that, nothing. This time I get an error 76.

Power supply light turns green.
When I turn on the 360, the splash screen will start. But before the ball stops rotating it will flicker and go to error code. I have tried with and without hard drive. Checked wiring to my dvd drive, but that seems to work fine. I can hear the CD spinning. My best guess is something on the mobo. Im gonna make sure everything is nice and screwed on, nothing loose tomorrow. Also going to try another power supply.

Any suggestions would be appreciated, I just find it weird that half way through boot it would error.
One more thing, right before I get the error, there's a high pitched squeak from the TV then it will go to error.

Very weird, i've had my 360 for about 5 months.