While en route from Singapore to Narita, Japan, a flight attendant proceeded to transfer a serving cart from the main deck to the upper deck. As the flight attendant pushed the cart into the lift, the lift began to move. The lift continued to raise, catching the edge of the cart and lifting it off the ground, trapping the flight attendant between the other end of the cart and the galley counter opposite the lift. As the cart was raised off the floor, the flight attendant was lifted off her feet and her body was pushed on top of the galley counter. The cart continued to rise, pinning the flight attendant’s face between the cart and the bins above the galley counter. An inspection of the galley lift after landing revealed a piece of cardboard had been inserted into the interlock safety switch, disabling it, and by doing so, the galley lift can be operated without closing the galley lift door. This condition is known to have been caused, in other incidents, by food service personnel to expedite loading of food service aboard the aircraft. Probable Cause: intentional tampering/altering of a galley lift interlock microswitch by unknown persons.