Recently I changed the motherboard (15CBHPGT) of my old laptop (HP envy 15t Q300) after HP-service confirmed the board was damaged. Now after changing the board and connecting only the power cord without the battery, the power LED is turning on but pressing the power button is not turning it on. No power to fan or HDD. I checked by disconnecting each connection, Ram, HDD, display but nothing solved the issue. I have checked the 19.5V to the board and the 3V to the power button. This is happening with the new motherboard. Can you suggest what I can check now?