Well there are a few different ways you can do this, either with Switches or with a Variable. I'll explain how to do it using a Variable since it just requires one variable instead two or more Switches.
Pick the order you want to use for the switch events; I'll name the switch events switch1, switch2, and switch3. An arguably better method than having a set pattern would be to make the switches random so it's different each time, but I'll just explain the basic way here.
All switches should be triggered by the action key and should animate to "turn" upon press. You will also need to set up a variable to use; I'll call it switchOrder.
switch1 should say something like:
Conditional Branch: switchOrder==0
set Variable: switchOrder=1
end
Else:
set Variable: switchOrder=0
(Animate all switches to go back to normal state)
end
-------
switch2:
Conditional Branch: switchOrder==1
set Variable: switchOrder=2
end
Else:
set Variable: switchOrder=0
(Animate all switches to go back to normal state)
end
------
switch3:
Conditonal Branch: switchOrder==2
(Open Door)
end
Else:
set Variable: switchOrder=0
(Animate all switches to go back to normal state)
end
-----
I don't have RMXP open right now so I don't know if that's exactly the syntax of how RMXP says everything but that generic code should work. Hope that helps, but let us know if you have more questions.