Xbox giving me a red dot on the power supply?

[360Player90]

Got given this xbox in exchange to flash another.

It hadn't been opened before and will not turn on, when i press the power button it make the sound but the light on the power brick goes red.

I checked all ports for shorts, tried a different PSU (even though it works on other slims).

Any ideas to what it could be? (checked the nand and other points and all look fine)

Could it have been dropped or water damaged? (no signs of physical damage neither, looks near enough new)

Few images if you can spot anything i may be missing:

http://imageshack.com/a/img594/4449/kbfw.jpg
http://imageshack.com/a/img24/2616/f688.jpg
http://imageshack.com/a/img827/89/5llk.jpg
http://imageshack.com/a/img834/3025/uu5n.jpg
http://imageshack.com/a/img543/2015/5l9r.jpg
http://imageshack.com/a/img89/8488/xmit.jpg
http://imageshack.com/a/img202/3175/qzw1.jpg
http://imageshack.com/a/img713/8271/a7uo.jpg

 

[xzanox]

Check the power plug entrance on the mobo. See if there isn't any damage from plugging the power cord. See if all of those golden colored tiny clips are in place.

 

[360Player90]

All seems fine there

 

[xzanox]

Yep don't see anything out of the ordinary neither there...so you can also scratch that from your list...

Southbridge issue possibly...

 

[Slayertex6]

Most likely the mosfet on the 12v rail.

 

[360Player90]

Yep don't see anything out of the ordinary neither there...so you can also scratch that from your list...

Southbridge issue possibly...

I may be wrong here, but if its a south bridge/nand/cpu wouldn't it give me a red dot on the RF board?

Am thinking its a short or something is blown for it to give me a red dot on the PSU.

 

[xzanox]

No SB can also give you the beep and red dot on psu...