1 In rare circumstances, your keyboard/device can become unwritable, and dfu-programmer will give you an error like this:
3 Erasing flash... Success
4 Checking memory from 0x0 to 0x6FFF... Empty.
5 Checking memory from 0x0 to 0x607F... Empty.
6 0% 100% Programming 0x6080 bytes...
8 Memory write error, use debug for more info.
10 Currently the only way to solve this is to [reprogram the chip via ISP](https://www.reddit.com/r/olkb/comments/4rjzen/flashing_error_on_mac_os_x/d52rj8o/). This requires another device to be hooked-up to a couple exposed pins on the PCB. There is a guide on how to do this [here](https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader), and [this is where things are on the Planck PCB](http://imgur.com/lvbxbHt).
12 An example command to flash the board once things are hooked up is:
14 avrdude -c usbtiny -p m32u4 -U flash:w:planck_default_rev4.hex