Answer:If none of the above reasons is true, Apple Boot.efi may be damaged.In this case, you may need to make a macOS recovery disk or contact Apple customer service for professional diagnosis and repair services
Answer:It is suggested that the memory can be increased when the former is better, and the former is better when the main frequency is higher, and the latter is lower. Even if the memory is increased, it can't be processed by CPU. As for SSD, it has been since 2015.
