Greetings,
I have 2 boards with the same problem. When I press the button, all keyboard LED light up and after 5-10 seconds the board turns off.
Board #1 had liquid damage around ISL6260 and BCM5751. Replaced ISL6260 and all 3 ISL6208.
Board #2 Got it for parts. Working fine until you touch the DC Jack, then the LCD loses picture and you have to unplug and re-plug the charger and then turn it on. It worked for 2 hours but then it stoped working and now it has the problem i mentioned above. Replaced ISL6260 but nothing changed.

I checked everything from this list: Условия для старта ноутбука and all voltages from page 3 of the schematic.
Changed BIOS chips and program them.

I dont know what am i missing. Probably i will have to check all voltages again.