A4988 current setting

I am trying to build a 3dpburner and the electronics portion is confusing me to death.  There is so much conflicting info that I can't figure out much of anything.

Right now the specific problem is getting the stepper to work. 

Here is where I am...

1 I f!ashed the custom grbl.  It seems to be functioning properly.
2 I installed the cnc shield
3 I wired 12v to cnc shield.
4.  I set jumpers to 1\16 stepping.
5. I installed one a4988 with enable pins aligned.
6. I plugged a stepper motor in pretty much blindly.  (Nobody ever mentions which direction it goes nor says it is universal.  The data sheet that came with motor also says nothing)

7.  Powered it up and read vref.  I think my target voltage is 2.5.  it was 1.9v.  so I barely turned  the pot clockwise.

8.  The voltage dropped to 0 and nothing I did brought it back.

9..figuring I all ready fried it I sent a move command and the stepper moved correctly.

10.  I figured ok.... Plan b.  Follow method where you turn it until the motor stops and then turn it back until it moves again.  Turned pot 1\16 counterclockwise and motor died.  Turned it back still dead.   Nothing I did made it work again.

So... How much do you think I destroyed?  Anybody have any more coherent instructions?  Also is the pot just supposed to spin forever?  If so which position is zero?

Typing on touchpad so sorry for typos