Your question is Debugging a Complex Issue. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain your thought process when debugging a complex issue.
Describe how you would frame the problem, gather evidence, isolate potential causes, coordinate with relevant stakeholders, and decide when to restore service or proceed with a fix. Explain how you would communicate status, manage uncertainty, and verify that the issue is resolved without introducing new risks.