Macbook A2141 and A1990 machines are great machines put out by Apple for their era but they both suffer a terrible design fault due to the electronics engineers and the case designers not knowing what the other was doing. Because of the layout of the electronics, the critical voltage regulators needed for powering the NAND SSD chips are exposed to an inevitable fate of failure from corrosion. If you're lucky enough to catch this fault before it has killed the NANDs / SSD you then have to hope that the workshop repairing your machine knows the safest sequence to restore access to your machine. There's no second chance.