Boot device not found

[Rex49]

please my laptop - HP EliteBook 840 G3, Intel(R) Core(TM) i7-6600U @ 2.60GHz has issue booting up. On the display on screen reads
"Boot Device Not Found,
Please install an operating system on your hard disk.

Hard disk - (3F0)

F2 System Diagnostics 
For more information, please visit: www.hp.com\go\techcenter\startup"

I can't even assess the above site on the system, how do I go about it?

[MysteriousMe]

Welcome to HP Support Community, @Rex49 

Thank you for posting your query, I will be glad to help you.

Boot Device Not Found Error on HP EliteBook 840 G3
If your HP EliteBook 840 G3 is displaying an error "Boot Device Not Found" with the code 3F0, it indicates that the laptop is not detecting your hard drive as a bootable device. Here is a step-by-step guide to troubleshoot and potentially resolve this issue:

Step 1: Check BIOS Settings
Restart Your Laptop: Turn off your laptop completely and then turn it on.
Enter BIOS Setup:
When the HP logo appears, repeatedly press the F10 key to enter the BIOS setup.
Check Boot Order:
Navigate to the "Boot Order" or "Boot Options" menu.
Ensure that your primary hard drive (usually labeled as SATA or HDD) is listed as the first boot device.
Save and Exit:
If you make any changes, be sure to save them. Press F10 and choose "Save Changes and Exit."

Step 2: Run Diagnostics
Run System Diagnostics:
Restart the laptop and press the F2 key when the HP logo appears to enter System Diagnostics.
Select "System Tests" and choose "Quick Test" or "Extensive Test" for the hard drive.
Follow the on-screen instructions to complete the test.

Step 3: Hard Drive Check
Reseat the Hard Drive:
Power off the laptop and remove the AC adapter and battery.
Open the back panel and reseat the hard drive to ensure it is properly connected.
Put everything back and try to boot again.

Step 4: Operating System
Check for Operating System:
Ensure there is a proper operating system installed on the hard drive.
If not, you may need to reinstall the OS using recovery media or installation disk/USB.

Step 5: Professional Support
If the issue persists, and the diagnostics show a problem with the hard disk, it might require professional repair or replacement.

I hope this helps.

Take care and have a good day.