Xbox 360 S - power chime, then powers off

[survivalbloke]

I have a 360 S here. I have a solid amber light on the PSU. If I press the power button, I get a chime and fan spins up, PSU LED turns green, then the unit immediately powers down.

What should be first steps?

video

[nick122]

Re: Xbox 360 S - power chime, then powers off

I'm a little late, but I think I can help. Usually when a slim board immediately powers on and then right back off, it has something to do with the main 12V rail PWRGD signal. For some reason, the southbridge isn't detecting the 12V PWRGD signal. The PWRGD signal could be missing because of a short on the main 12V rail, a bad HANA which doesn't generates the PWRGD signal when it should, or a bad southbridge that doesn't recognize the signal.

Keep in mind that it can also be caused by a bad power supply, although that doesn't seem likely, given the fact that the fan spins for a brief second, suggesting there is 12v getting in. I'd start by trying a different PSU and go from there.