Elitebook 820 G1 not booting - searched LED sequence but can't find answer?

[ADB100]

I have an Elitebook 820 G1 that has been working for ages.  Today it won't boot up.

When I press the power button the button illuminates but dimly for 6-seconds - synchronised with this is the power LED that goes white for 6-seconds. This then goes out and the charging LED flashes very quickly orange, white, orange, white, orange then goes out.  There is no other activity.

I have removed the battery, the CMOS battery, reseated & replaced the RAM, removed the SSD, removed the WiFi adaptor and even removed the keyboard but the behaviour is always the same.

I can't find any references to the LED sequence and I have tried everything I can find online about holding buttons down whilst trying to power on etc.

Any ideas or is this destined for the bin?

[Lil_Boy_Blue]

Hi
First:- Turn off the computer, press and hold the PWR button for 4 seconds.

Then - Leave only keyboard and mouse connected, disconnect all externally connected
devices such as Docking Station, USB storage devices, displays, and printers.
Unplug the AC adapter from the computer.

Next - Press and Hold the Power button for 15 seconds to Hard Reset.
Rinse and Repeat; Re-Connect the AC adapter.

NOW begin checking/testing/proving the Hardware is fit for purpose.
Power on your PC, press ESC (repeatedly), then F2 at the prompt.
Choose System Tests (Fast Test does a 4 minute hardware check).

Hopefully that runs satisfactorily.

[ADB100]

Hi, thanks for the reply but your suggestion makes no difference. The behaviour is exactly the same.

Just noticed that if I put it into the Ultra Slim docking station the charging LED illuminates, however it still won't power on.

When it is in the docking station the power button on the laptop or the one on the docking station don't do anything.  It only goes through the power, charging LED cycle described above when out of the docking station (with battery or external power connected).

I think the motherboard or CPU are fried.  No idea why though.....

[ADB100]

Hi, I have tried everything and the only response out of the laptop is the LED sequence I posted a video of.

I think the CPU has failed.

[ADB100]

I purchased a used 820 G1 motherboard with an I5-4200U CPU and replaced it and its now working.

I think the CPU failed.