Help in determining meaning of blinking light sequence

[kugelblitz]

My HP Zbook 15 G2 laptop had been running for several days until I came to it with a blank screen and the machine appeared to be off. When I attempted to power it back on it would not, only a blinking light error code. I disassembled the laptop to diagnose the issue, disconnected all peripherals, even the power button. Still when the AC power was plugged in, the display did not turn on and the blinking error lights showed. I've tested with a multimeter that the AC adapter has 19.5V when plugged in and also that the mother board is receiving 19.5V from the power connector cable. This link explaining blinking light codes for HP laptops does not appear to have the sequence I am seeing. It happens so fast that I'm having a hard time identifying the blink sequence as well. I've captured a video of the light sequence here. The fan starts briefly and then stops. Can anyone point me to the documentation for these blinking lights and/or help identify them for me? I've inspected the motherboard for burn areas that might indicate a short, but haven't noticed anything. I've disconnected the CMOS battery and fully discharged the motherboard, by holding the power button for 30 seconds with no battery or AC power connected. It would be easy to guess that the motherboard is fried, but I'd like to more assuredly diagnose the issue. For instance, could it be due to a faulty fan assembly? Should the motherboard bootup fine with all the peripherals disconnected? Or have I incorrectly eliminated peripherals as the source of the issue? TIA

[Huffer]

You have done a good job of diagnosis. Yes the system should boot with all peripherals removed. Blinking light codes are unreliable when the motherboard is dead as appears to be the case with your machine. Sorry.