Technical approach implemented as follows:
-Added a new sys choice on State field of Case table labelled as 'Re-Opened' and with value of '2'.
-Created a new Customer Service Case Flow called 'Re-Open Case', which is responsible for the transition of state from 'Resolved' to 'Re-Opened'.
-De-activated OOB button called: 'Open Case'.
-Created a new button called: 'Re-Open Case', which will carry out the state transition specified in the new Customer Service Case Flow, as mentioned in step no. 2 above.
-Updated the existing flow formatter [sys_process_flow] called: 'Assigned' by modifying the condition field to cater for the 'Re-Opened' state as well as the 'Assigned' one, i.e. State=Assigned OR State=Re-Opened.
-Finally, updated the client script called: 'Hide Options From State Field' to hide the 'Re-Opened' state value from the drop-down list when the current state is NOT Re-Opened.
reopened correlates to 'assigned' in the flow formatter: