Xbox Shuts down by itself from playing halo 3

The link to
support.xbox.com/.../console-turns-off-unexpectedly worked for me. My xbox used to shut off and the problem started after an update i believe which set the default setting of AutoOff feature to 1 hour.

I don't know what to tell you, you'd need to start by replacing the power supply somehow. I don't know what you'd do in a case where a repair center is not available in your location. XBOX Live isn't even available officially your region so you wouldn't
be able to get an official repair unless you sent it back the region where you purchased your XBOX 360 from.

Hello Hassassinade thanks for your reply

i dont have wall outlet that has with three holes (that's why i use a power strip) but wall outlet extension can do? (just wanna ask) or it really need the main outlet? i will try your suggestion when i get back home. and i dont think i can request a new
power supply from microsoft cause there is no philippines on the selected country

Try getting a microfiber cloth and wipe the power button and the disk tray button. Sometimes oils in your finger gets on the buttons forcing it to shut down.

If it's new enough, I would take it back from where you purchased it from or send it back for repair. If you mess with it in any way with it being under warranty, you could in fact void the warranty by messing with it.