PLEASE HELP! Service Mode Protected

[SpeediGary]

I'm trying to change a print head on my vp-540 but when I turn on sub power while holding the left right and down buttons it says that the "Service Mode Is Protected" what does that mean and how do I get around it?

 

[Solventinkjet]

With the back power switch on but front power off, hit the following buttons in order:

Down, Right, Left, Up, Right, Down, Left

Then push and hold Left, Down and Right keys while powering on.

You must do this within 5 seconds so it may take a couple tries.