So I did everything you said. I heated up all soldering points. Still weird glitchy stuff happening. The glitchyness was slightly different, I could go into detail. But finally I got the idea to change the jumper from BUS to REG, so I get the 5V from the onboard regulator. Now everything works fine. I could have saved a lot of time and work if i tried that earlier. I would still like to know why it acts weird when I set it to BUS. I am guessing this just means that 5V from my power supply might be faulty (I have never tested the power supply with anything else before). Maybe I should try a different power supply. Or what else could be a possible reason?
