mac pro mid 2012, firmware for hgih sierra ffs

[chazzy2501]

ok, 10.8.5 to high sierra, mac informs me I need a firmware update. Press the shutdown icon, type admin password, wait for power off.

 

ok, I'm supposed to press the power button until a light or a sound happens.... This is where I can't follow. The INSTANT I press the powerbutton the PC fires up ok, but then it just boots back to the OS and gives me the same instructions? ok do it again.. this time ignore the mac powering on INSTANTLY and continue holding the button, so now the mac turns off, then a red light comes on inside, hold the button for a full minute....nothing else happens. ok short press and the mac boots back to the os (but now with the fans on full speed). same instructions.

 

 

ffs

 

 

tips?