Preston Garvey stuck underground (Fallout 4)

We went with Preston to the castle, he fell behind in a shootout somewhere along the way. When I got to the castle, I built a terminal, chose the option to track this character. He ended up in Greygarden. Came to Greygarden, the pointer points underground. I can only hear Preston, I can't give a command. I'm playing on survival difficulty, so the console doesn't work, rebooting didn't help either.