An employee was in a tunnel freezer, which was being turned on for the first time. The baffling for the evaporator fan got stuck in the siding. The employee ascended a 5'9"-tall cart to reach the raised baffling panel. The raised baffling shifted and dropped, trapping the employee's arm between the aluminum and foam core baffling. The employee sustained a severe laceration to the lower forearm/upper wrist and severed ligaments. The employee was hospitalized.