Thanks @tele_player. I have other Axolotis working fine with all the GPIO connected.
I have another with a damaged GPIO but it gets data, although it has an erratic behaivour.
What is happening with this is a very weird problem because it crashes.
I have soldered carefully the pins row and just tried with the pot.
I hope someone has a solution specially in this moment when to get new Axolotis cores is not easy without available stock.