The micro:bit's I2C bus is not working, the device might be physically damaged.


Check the micro:bit for any physical damage, ie a missing component. If this is the case, contact the reseller from which you purchased the micro:bit and ask about their replacement process or open a support ticket including a photograph of the front and rear of the device, the DETAILS.TXT file from the micro:bit and any information about the device and editor you are using to program it.