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At first there was no power on and there was no voltage on PPVCORE_GPU i changed U8900 then now i have the PPVCORE_GPU 0.9V, the logic powers on but there is no image.
Is not LCD issue, if also missing external video.
There must something related with GPU, or GMUX.
You can try hardware mod to disable GPU, just in case.
Supposing that you really have USB activity, not just steady light.