Recovery Mode key shortcuts (all three) not responding

First High Sierra is not officially supported on a 2008 system. AFAIK Apple only officially supports up to 10.11 on this system.

You will either need to reinstall from an original retail DVD of OSX 10.6 Snow Leopard or you will need access to another Mac to create a bootable macOS USB installer (macOS 10.11 El Capitan).

Hmmm, do you have Filevault enabled?

Sys Prefs>Security & Privacy>Filevault

Oh wait, older Macs can't do some things like Restore...

1. Start up from macOS Recovery

To start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following combinations on your keyboard. Command-R is generally recommended, especially if you never installed macOS Sierra 10.12.4 or later… https://support.apple.com/en-us/HT204904#notupdated

Command (⌘)-R

Install the latest macOS that was installed on your Mac.

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

Shift-Option-⌘-R

Install the macOS that came with your Mac, or the closest version still available.

Do you have an Old Install Disc for it?

Can you answer this?

Open Keyboard Viewer & see if those startup keys get highlighted when pressing them.

Are you using aWireless KB or a more useful & reliable USB KB?

Does it bootup still?

If so open Keyboard Viewer & see if those startup keys ket highlighted when pressing them.

So it doesn't start up?

And what is the exact model of the computer?

What version of macOS is currently installed?

Hi guys, Im trying to erase an old Mac I have in order to use it as a backup machine but I cannot reach recovery mode from the starting screen. Any suggestions? 🤔