Hi,
Probably you have a problem with the Power Supply. I don't now the model of your PS3 but there is one solution for this with PS APS-250. I think that APS-270 is the same but I am not shure. If the model of your PS is the same you can try. First disassemble the PS. In the up-middle side you can see two potentiometers. Mark them and turn them left arround 5 degrees.
I uploaded some pictures here.
https://plus.google.com/u/0/b/116883850378439288406/photos/116883850378439288406/albums/5977278861169015649/5977278869599156818?pid=5977278869599156818&oid=116883850378439288406
Here's how to Unplug the power supply:
[guide|3225]
Regards.