The E6V2 has been available with either a Bootmapper Client or QMK-powered PCB. During the second round, the QMK-powered and BMC PCBs were redesigned, and used different ports and a different switch matrix.
Please use the appropriate version when making your firmware. Flashing one in place of the other, can brick your PCB. Please be certain whether you have a OE or LE PCB.
See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).