Self Test Fail after flashing firmware

[tobias]

Great, now we know the problem, however I have a suspicion it can actually be the MPU9250 (which is passing through the I2C) which has soldering problems. This is a know problem. So if you decide to give it a try to fix it I would start with reflowing that chip. We have made an instruction video how to fix it with a hot air station. If it that doesn't work out just contact us and we will arrange a replacement board.