I don’t know the difference between a jumper and a short circuit, so it took me a while to figure out why I couldn’t upload a program ( okay firmware ) to my make controller a second time. After reading in the documentation about the ERASE pin and SAM-BA on the forum, I wasn’t any further. Where the heck is J2.21? What is a jumper? How do I short?
Fear not, gentle reader... The little plastic square guys are jumpers and you can temporarily borrow one from the board. Just make a mental not of it’s position, so you can put it back. Look inside the jumper and you will see metal contacts. Here is my controller with a jumper sticking up off the board.

Place this on the 3rd and 4th pin in from the left on the back row as you see here in the photo. You will notice that whatever program was running will now freeze. Congratulations you just shorted the ERASE pin and your controller will reboot into sam-ba mode. You can also use any peice of metal to make this reset happen.

Uploading new firmware on Make Controller
After the first time you upload firmware with mchelper here is the processes for uploading your new firmware onto the Make Controller.
- Short the jumper
- Power cycle the controller
- Upload firmware with mchelper
- Power cycle the controller