“My alarm didn’t go off” works once. Twice, and the alarm isn’t the problem.

The first time, people take you at your word, because phones do fail and everyone has had a bad morning. By the second time, the pattern is more convincing than the excuse, and what they hear is that getting there on time is not something you have solved. Blaming the alarm also means there is nothing for you to change.

If you are late the same way twice, treat the cause as the night before. Move one thing earlier: the charger across the room, the bag packed, the phone off at a set time. Fix the setup and the mornings mostly handle themselves.