also there are two small cips near the lcd that are delivered after the controllers are delivered during construction. This is so they can legaly remove them when they loose the job as they are not part of the original controller(tricky). Without these chips the lcd is limited and laptop does not work. Make sure the owner keeps these chips. They are Small and located behind a black cover that slides up the opens. The elevator will work normally without them but later on when diagnosing you will be up the creek