Even if there is no OS, wouldn’t the machine get to the initial BIOS screen?
Or maybe not - I’ve had machines get to BIOS and report a bad HD or missing (cable pulled out), but never tried firing up a machine with a functional HD and no OS.
Does it have a floppy disk drive or USB port?
You might try booting from a thumb drive.....
“...wouldn’t the machine get to the initial BIOS screen?”
You might try different keys while booting to get to the BIOS. [Find the motherboard mfg and model number. Get the manual and read it.]