Goal: For there to be no open tickets over 24-hours on weekdays.
Go back to the filter in the ticket view and change it by removing the two groups and changing to "Open" in the status.
Then also put it in ascending order so the oldest are first.
This now gives you all of the "open" tickets. Cycle through them one at a time and check when they were created. If they are over 24 hours old, send a note to the assigned agent asking them what they want done with this ticket.
If it is not yet assigned to an agent, first look through the thread to see if there was "any" agent contact. If so, contact that agent. If not, send a note to the supervisor* of that group asking them to deal with the ticket or assign it to someone.
If the assigned agent does not reply, contact the supervisor and assign this ticket to them. If neither the assigned agent nor supervisor replies in 48 hours since the ticket was opened (either at creation or when reopened), escalate this ticket to Tier 3.