What would be a good way to overcome bad experiences with a professor in my department, who is not my main advisor, but from whom I would like to get advice regularly?
During the first year of my PhD, I worked with the Professor in a class on a project that I didn’t perform well on (because I was not very interested in that particular project + I didn’t feel very confident on the topic by that time). Our relationship has cooled down since, and he was even debating whether or not to put me as a co-author on the paper that came out of the project with multiple students. (the authoring-issue is not part of this question; I mention it to describe the status of our relationship)
Now in my second year of my PhD, I realize that it would be quite valuable to have his advice on other projects that I work on, potentially even as a co-advisor, but I fear I messed up the relationship too badly.
What would be a good approach to overcome the bad/non-existing relationship? Or would that be a waste of time and I’d rather look for someone else, which could potentially even mean I need to change the focus of my PhD?