HP G62-DA0AX1MB6F1 doeas not swithes on, I did this:
1. sew bios and EC with true Hex files.
2. changed KB926QF-D3 ----->KB926QF-D2(ORIGINAL ONE)
3. CHANGED BD82HM55 BY NEW ONE.
but now when plug power jack, power jack led goes on(white), but wen press power switch ,power jack led blink 3 times and its color goes orange.
What I must to do? I am really confused.
Somebody help!!

there is another M.B just like this, But this M.B works fine but sometimes it cannot power up( Power led goes orange and blink 3 time just like no power board). I looking for error description and fine where to dig for this error.

There are not any voltage measures from you.
Whats going on with signals on EC?
Looks like a problem with a PWM.