Do not connect the 3.3V pin, using a simple ebay ST-Link! That will kill the 3.3v regulator, which results in almost having a short in the 3.3v rail. The 3.3v on the swd connector is only for sensing 3.3v with the st branded stlink programmers. When using the small eBay stlinks the 3.3v should be left unconnected. The vesc 4 did not have this problem since it uses a different regulator. Fixing this is easy if it should happen, the VESC will work again after replacing the 3.3v regulator.
Array of VESCs:
Always use Can Bus! A parallel harness (e.g. Throttle via ADC, PPM etc.) will for sure fry your VESC SIX. The Pins are partly connected to the sensitive MCU-Chip directly. So if you are not keen to to solder on a new STM32, use CAN-Bus.
Bluetooth and other extension modules:
Hexacopter mentioned it already. Equipment that was designed for VESC 4 should not be used with VESC Six, until the vendor has stated that it is compatible. Read more about this in Hexacopters thread about the metr.at bluetooth module.
The printing on the sensor port is wrong. So please refer to the manual for correct pin assignment.