Execute a CAB-approved production change

Reinforce the change-enablement order from ITIL training. Implementation does not start before the window, backout, and approval are confirmed. Failed validation triggers backout as its own action.

1. Confirm CAB or emergency-change approval for this window.
2. Verify the backout plan.
3. Verify the success criteria.
4. Place the change freeze or maintenance banner if required.
5. Implement only the approved steps.
6. Run the documented validation tests.
7. If validation fails, execute the backout plan.
8. Leave a failed change open for reassessment.
9. Close the change with evidence after a successful validation.