I don't really like the term "fail" to describe a Sprint, but the primary objective of a Sprint is to deliver the Sprint Goal by the end of the timebox. I suppose you could consider "failure" to mean not delivering on the Sprint Goal, but I'm still not a fan of considering it a failure.
The Development Team are the best people to identify when the Sprint Goal is at risk. The Daily Scrum is an opportunity for the Development Team to inspect their progress toward the Sprint Goal and replan to maximize their chances of meeting it. If the team has concerns about their ability to meet the Sprint Goal, they should be raising these to the Product Owner and Scrum Master who, in different ways, can help the team to understand and focus on getting the valuable work done and ready for delivery.
I would facilitate the Daily Scrum by asking questions. If I don't hear the team talking about the Sprint Goal or the work associated with Product Backlog Items associated with the Sprint Goal, I'd ask about those. I would also look at time in the state, once work starts - is something "in progress" for a long time, or waiting for code review for a long time, for example, and ask about those. Some kind of visual aid is nice - I prefer a Kanban board with the Sprint Goal and work item aging visible since it can help focus the discussion on the goal and progress of work items (including blocked items). Depending on the maturity of the team, I may set aside some time for coaching on the Daily Scrum and figure out what they think would be good to help them focus on the Sprint Goal and help them set up an appropriate space with that information or visualization to guide their planning and discussions.