Why doesn't my Toshiba Satellite L750D power on?

Hi everyone,

I had my Toshiba Satellite L750D which is not power on.

Power light show Green; Battery light charging show orange, when press power button, an 3rd light lights ON but nothing appear.

I had tested:

- Remove LCD cable, still not boot

- Remove USB side board, still not boot

- REmove HDD; still not boot

- Remove Memory; still not boot; no beeps sounds

- Remove CPU, clean fan, repaste the CPU core; no difference.

- Remove keyboard; still not boot.

Could anybody known, or know a way to find what is the problem with my portable computer or an common problem with that model? Thanks.