I recently had an problem with laptop HP 625 blank/black/no screen. As I've followed the HP instructions, I've discovered that 5 times blinking caps lock means only one thing: MOTHERBOARD REPLACEMENT.
So I needed to order another 611803-001 motherboard. That was successfully replaced yesterday. Now the laptop starts and the fan is working normally (before it didn't). I receive no caps lock blinking anymore. But still get no screen.
Because I thought there was probably some bad contact with the screen, I've decided to plug in the VGA cable, to see if screen will be allright there. "No signal", no success. Reseting CMOS and following the bios hard reset procedure (AC adapter, battery, peripherral devices, etc. OUT, hold power button for ~15 seconds, AC, bat. back and power ON.) but without success.
Thank you for posting. I have read your post, and I understand that you have replaced the motherboard of your laptop, but it starts with no screen display, and external monitor did not work either. I want to assist you in this issue.