Once a change has been approved by the change management review board, the next step is to:
Implement the change: This involves carrying out the approved change in the system or environment according to the change plan.
Perform risk analysis: This should be done before the change is approved to assess potential impacts.
Assign a change coordinator: This role should be designated earlier in the process to oversee the change implementation.
Verify testing results: This should have been done before seeking approval from the review board.
Reference:
CompTIA A+ 220-1102 Exam Objectives, Section 4.2: Explain basic change-management best practices.
Change management process documentation.