MY HP Probook 455 G3 wont start

[Shivansh41]

MY Proobok was working fine all morning when suddenly it stopped and is not turning back on.

when i start it without power cable attached it's power button and and caps key light up for a few sec before switching off again,

with the power cable attached it does not do this even.

When i tried to start my probook without battery and a power cable attached , it does show a white charging light for few seconds and power button light up but this turns back off.

(none of the keys blink)i tried a hard reset but nothing works😔

[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

AND/OR - Power on your PC, press Esc (repeatedly), then F2 at the prompt.
Choose System Tests (Fast Test does a 4 minute hardware check).
AND/OR
HOW DO I USE DIAGNOSTICS?

HP PC Hardware Diagnostics Windows is a Windows-based utility that allows you to run diagnostic tests to determine if the computer hardware is functioning properly. The tool runs within the Windows operating system in order to diagnose hardware failures. HP PC Hardware Diagnostics Windows comes pre-installed on new HP computers, but if not on yours, download here:- http://ftp.hp.com/pub/softpaq/sp93001-93500/sp93457.exe

[FoolishMortal]

I have the same issue with the same model laptop.  The machine does not startup at all.  Holding down the power button for 15 seconds has no effect.  AC adapter plugged in or not plugged in.  Makes no difference.  Running system test is not an option as the BIOS does not start.  I am concerned it is a hardware issue on the motherboard.  Any suggestions

[Lil_Boy_Blue]

Hi
Hopefully one of these documents will cover (and solve) your problem...

https://support.hp.com/ca-en/document/c00042629

https://support.hp.com/us-en/document/c02693833

Turn off the computer, and then connect the power cord.
Press and hold the Windows key and the B key at the same time, and then press and hold the power button for 2 to 3 seconds.
Release the Power button but continue pressing the Windows and B keys. You might hear a series of beeps.
The HP BIOS Update screen displays and the recovery begins automatically. Follow any on-screen prompts to continue the startup to complete the recovery.
HP BIOS Update recovery in progress

If the HP BIOS Update screen does not display, repeat the previous steps but press the Windows key and the V key. If the screen still does not display, your computer might not support the feature or there is a hard drive issue. Continue to the next step to install a BIOS recovery file from the HP website.
If the Power light turns off, the Power button was held too long. Repeat the previous steps, making sure to hold the button for only 2 to 3 seconds.