The flight instructor reported that during a flight review, the pilot being reviewed was performing a pinnacle approach to landing at a selected site between 3,500 feet to 4,000 feet mean sea level. During the approach, the helicopter was descending at a rate of about 400 feet per minute and a forward speed of 30 knots. The pilot stated that the helicopter was passing through translational lift and that it seemed like it was taking more power. The flight instructor called for a go-around due to the indicated airspeed and the high sink rate. The instructor stated, “Upon initiating the go-around we experienced lack of power, decreased rotor rpm, and an increased sink rate.” Both occupants reported that they pulled their collectives up to cushion the landing, however, the touchdown was hard. The helicopter tipped forward onto its nose and rolled onto its left side. The landing skids were spread and bent, the main rotor blades remained attached, but were bent, and the tail boom was bent. The flight instructor reported that there were no mechanical anomalies with the helicopter prior to the accident.