5pin Midi Input not working

[Blindsmyth]

Happy holiday everyone!

I have axoloti board with an unresponsive 5 pin Midi Input. I have tried hooking up the midi in to the out and sending in data from another axoloti, nothing worked. The same patches and setups worked on the other board.

I have soldered this pin headers and tried to hook something up there too with no result.

Is there a chance that I damaged something buy soldering in the pin headers? It doesnt look like something's damaged.

[Blindsmyth]

any suggestions what the problem is @johannes ? I tested in every possible way, fact is that the midi input is not responding!
Since I want to send midi back and forth two Axoloti Boards I was thinking If it was possible to skip the octocoppler. Would that be possible and are there pins for that?