PlayStation 4 Pro, brand new, 3 beeps

I have just returned and replaced a PS4P that I believed was DOA after all it gave was 3 beeps.

I have set up the replacement and I am getting 3 beeps again.

Am I doing something wrong or have I been really unlucky?

I have tried. - running directly from the plug socket (currently on a multitap but only the PS4P and the TV are running off it and the TV works fine.

Any other ideas?

_{Answer based on comments above}

Given that the system is brand new, you were likely pressing the eject button instead of the power button. If that is the case, then this is standard behavior for the PS4 Pro.

On the PS4 Pro, the eject button is located on the right of the system directly above the USB ports. The power button is located on the left side of the system. If there is no disc in the system, pressing the eject button will cause the system beep 3 times consecutively to indicate there is no disc to eject.