Dortmund did have a high mentality in the Champion League match but now everything is different because it is not only the mentality that determines but the strength and performance of a team that we can see as a whole this season.
Dortmund's performance this season has been inconsistent even though after changing coaches their performance has improved slightly and even showed impressive performance in the Bundesliga but what happened in the first leg against Lille proved the fierce competition in the Champion League.
You are right because mentality cannot always save them to rise to win the match in the second leg. If Dortmund does not try to do their best then it is not impossible that they will be eliminated in the next match. Dortmund still has a chance in my opinion because if you look at the quality of the team it should be much better than Lille and in terms of experience they are also superior. But that's football because sometimes things that are considered impossible can happen and vice versa Dortmund who are much more superior could experience a much worse fate this season.