Firstly I must make you aware the A4988 boards I am using aren't official Pololu drivers, I hope you can still find it in your heart to help me out.
I have two makes, one Sainsmart (black, the one that exploded) and on RepRap (blue, that I thought I had blown up but it turns out I haven't)
I got a replacement Sainsmart one because I am on a tight schedule and I could get one next day delivery.
I am wiring both boards up exactly the same (per the PololuPres_V3.pdf)
The strange thing is, the RepRap one provides a 500mA at 12v when testing between the coil. However, the Sainsmart one provides just 20mA with exactly the same wiring. I have adjusted the potentiometer however nothing happens and I am careful to turn it too far incase it sets on fire too.
Any help would be much appreciated.
Thank you in advance.