Is this a 21.5" model? If so the internal SSD ( which would be placed under the Optical Drive will NOT be compatible with the original main logic board that it came with. It would need a different logic board, cabling, and housing and the SSD would have to be from Apple. Swapping the HDD will cause issues as the sensors are now built into the Apple HDD parts. Hope this help!

The older models of unibody at first did not have the additional tab that Mayer is referring to. If yours is one of those models, use a bit of kapton tape on the wide rear part of the cable so the tape is sticking straight up above the mlb so you can to be able to move the cable and therefore slide the portion into the connector on the board successfully.

You have probably had some wine get on the main logic board and possibly the topcase. ( Power button is affected when topcase has liquid interaction.) If you are comfortable taking the unit apart you may need to remove all the main parts, clean the parts carefully with alcohol (90% +) let dry COMPLETELY and then attempt a reboot. Please include the exact model of MBP that you have for me to be clearer as to the configuration of the Power button parts.

With some of these units and past versions of the MBP, if you carefully use a paper clip stretched open and put it in the headphone jack and carefully use it to manually turn the part which senses if the sound is input or not it will sometimes clear the issue. It may have to be done more than once or it may not work but occasionally it does solve the problem.

The cable from the Powerbook display is not compatible to connect to the Macbook Pro logic board so you can't interchange these parts.

You are most likely correct that the keyboard needs replacement but I would first attach a USB keyboard to your MBP and test those same keys with the duplicate characters. If the external keyboard functions correctly then just replace the MBP internal keyboard in the top case.

Unfortunately no you can't do this upgrade. The two units do not have compatible cage fans as the 2008 has two riser cards for the memory and the 2010 has a board that is called the processor tray vs the backplane board ( older models this was referred to as the main logic board. ) The 2010 processor tray is a tray that holds the ram, heatsinks, and processors. The 2008 Mac Pro had the riser cards that only contained the ram. The heatsinks and processors were attached to the main logic board. The upgrade will not be possible and wouldn't function properly.

The trackpad for these models of Macbook Air( original, late 2008, mid 2009) are not usually sold independently and are integrated into the top case and are different part numbers.

The A1150 is a core duo model and the A1211 is a core 2 duo. The parts that Apple specs to use as a top case for these models are different. Most likely you can't use the other top case as the wiring will be different between the two models.

The diagnostic LEDs are located to in a column next to the memory slot. Please see the image below. LED 1 : Trickle power from the power supply to main logic board. LED 2: Main logic board has detected trickle power from the power supply when the unit is powered on. LED 3: Computer and video card are communicating with each other. LED 4: Computer and LCD panel are communicating with each other. Update: