How can I restore a very old Mac mini?

Hi, I have a very old Mac mini that I haven’t used for over ten years so can’t remember the password.

I watched and read numerous tutorials telling me to press command+R, and many other combinations.

I started with a wireless keyboard and got know where so have bought a basic wired keyboard (every tutorial or advice said it doesn’t matter if it’s a windows or not).

I can confirm the keyboard lets me type in the password box but none of the following work;

• windows button + R
• windows button + Alt + R
• windows button + Ctrl + Alt + R
• Alt + R
• Alt + Ctrl + R
• all of the above but with F10

The only thing that does anything different than a standard start up is if I just press Alt on its own, it takes me to a grey screen and shows a hard drive with an arrow under it. If I press the arrow it takes me to the normal start up. As pressing the Alt key does this in makes me believe the Mac mini is reading the keyboard.

For information, there is an Ethernet cable attached to the unit.

Can anyone shed some light on this and help please?

im happy to loose everything on the unit.

Thanks in advance.

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