This macbook has been through many semesters of college, and was starting the second go around. The initial problem was that the bottom cover had many cracks and a piece broken out around the mag connector. Because of this, many arks and sparks happen while plugging into the charger and the battery would no longer indicate charging status. First part replaced was the original battery, (needed but no help). Macbook ran fine as long as it was plugged into the wall outlet. So I searched the web to try and find similar problems and solutions. The only one that came close to my failure was the replacement of the logic board. His only problem with this fix was that it only lasted about a week and failed again. I suspect that this person failed to adequately prep the heat sink pads and component with ArctiClean and create a good thermal connection with Arctic Silver Thermal Paste. So using your guide, I disassembled the Macbook and replaced the logic board. I also replaced the mag connector which actually could have been the only problem in the first place, but I had all the parts and just replace everything. Works great and my daughter believes I can fix anything.
The repair went well. About 45 minutes to disassemble and about an hour to put it back together.
Understand that the small connectors on the heat sink pull straight up, not out from the logic board. Maybe these had been very hot at one point, but were almost welded to the logic board connectors. Pulled the connectors off the pcb pads.