I have gone through your Post and would like to help
Please check in BIOS and let me know if you see the green line
Shut down the computer and upon restarting keep tapping on F10
Keep me posted
If the information I've provided was helpful, give us some reinforcement by clicking the "Solution Accepted" on this Post and it will also help other community members with similar issue.
KrazyToad I Am An HP Employee
Be alert for scammers posting fake support phone numbers and/or email addresses on the community. If you think you have received a fake HP Support message, please report it to us by clicking on "Flag Post".