The next step that the technician should do after replacing the power adapter and turning on the media player is verifying there is full system functionality. Verifying there is full system functionality is the fourth step in the troubleshooting process, after diagnosing and resolving the problem. Verifying there is full system functionality involves testing and confirming that the problem has been fixed and that no new problems have been introduced by the solution. Documenting the findings/lessons learned is not the next step after replacing the power adapter and turning on the media player, but rather the last step in the troubleshooting process, after verifying there is full system functionality. Documenting the findings/lessons learned involves creating a record of the problem and its solution for future reference or training purposes. Implementing the solution is not the next step after replacing the power adapter and turning on the media player, but rather part of resolving the problem in the third step of troubleshooting process. Implementing solution involves applying the chosen solution to fix problem. Researching knowledge base is not next step after replacing power adapter and turning on media player, but rather an optional step that can be done before diagnosing problem in troubleshooting process. Researching knowledge base involves finding relevant information resources to help solve problem. Reference: The Official CompTIA IT Fundamentals (ITF+) Student Guide (Exam FC0-U61), Chapter 2: IT Concepts and Terminology