Your question is Troubleshooting Jenkins Deployment Failures. 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 how you would troubleshoot a failed deployment in a CI/CD pipeline using Jenkins.
Cover how you would isolate whether the failure originated in the Jenkinsfile, source checkout, build agent, dependency installation, automated tests, artifact publication, credentials, deployment target, or post-deployment validation. Explain the Jenkins interfaces, logs, and command-line checks you would use, and describe how you would recover safely without masking the root cause.