I've just changed board for an HP Notebook 15 BS020WM. Since then, i've been having black screen at times with caps lock blinking ( 2 slow blink + 2 quick blink). It happens mostly if i restart the machine then i have to force shut down and it boots normally. I've already injected serial number for the new board. SN : CND7274SVS. I've also changed the CMOS battery.