I am attempting to confirm a BIOS Rollback, Current version F.26 Rollback F.20

[ErikaPillsbury]

Help, my computer will not not open anything except a blue square on a black background saying boot device not found.  Please install an operating system on your hard disk  Hard disk-3FO   f2 system diagnostics with a keyboard underneath

[Hawks_Eye]

Hi @ErikaPillsbury 

Welcome to the HP Support Community! We're here to help you get back up and running.

Thank you for explaining the situation clearly. Since the notebook is showing Boot Device Not Found (3F0) and you mentioned the BIOS rollback from version F.26 to F.20, let’s go through the recommended steps to address this.

Run HP PC Hardware Diagnostics (UEFI)

• Power on the notebook and immediately press the Esc key repeatedly until the Startup Menu opens.
• Press F2 to open HP PC Hardware Diagnostics UEFI.
• Select Component Tests > Hard Drive > Quick Test.
• Follow the on‑screen instructions. If prompted, continue with the Extensive Test.

Check BIOS Settings

• Restart the notebook and press F10 repeatedly to enter BIOS Setup.
• In BIOS, confirm that the hard drive is detected under System Information.
• Press F9 to load BIOS defaults, then press F10 to save and exit.

Perform a Hard Reset

• Disconnect the power adapter.
• If the battery is removable, take it out.
• Press and hold the power button for 15–20 seconds to discharge residual power.
• Reinsert the battery (if removable) and reconnect the adapter.
• Power on the notebook again.

Use HP App – Diagnose & Fix

• If the notebook starts after the reset, open the HP App.
• Run Diagnose & Fix to automatically check storage and boot configuration issues.
• Follow the guided steps provided by the tool.

Reseat the Hard Drive (if applicable)

• For models with accessible hard drives, ensure the drive is properly seated in its bay.
• Refer to your notebook’s maintenance guide for instructions.

For complete guidance, please refer to HP’s official support document here:
HP PCs - Hard disk 3F0 boot device not found error | HP® Support

The error indicates the system cannot detect the operating system on the hard disk. Running diagnostics, checking BIOS detection, performing a hard reset, and using the HP App’s Diagnose & Fix are the key steps to resolve the issue.

Take care, and have an amazing day!

Regards, 

Hawks_Eye