S3 No speed shown on display

I bought a faulty S3 for a good price. After taking it apart, I discovered that the motor cable had a broken wire near the socket. I soldered it back together, tested all other wires as well and they all made connection. So I assembled the bike again, but it still did not show any speed when spinning the wheel. I took out the motor and tested the hall effect sensor. When holding a magnet close, it sends 0V over the signal wire. When removing the magnet it goes back up to 5V. So that seems to be working as well. Is there anything other I should check? The bike gives no errors at all, not even when the motor cable isn’t connected.