Chosen Solution
Hi! I have a Mid 2012 Macbook pro and for the past 4 years It´s been running fantastically with a Crucial MX100 500GB SSD. Running high sierra 10.13 Last night though, The laptop failed to boot, showing me the dreaded folder with the question mark. I tried internet recovery, single user long on etc etc without any luck. I then booted from an USB HDD (original internal drive + enclosure), and was able to see that the disk was recognised but it said that it needed to be fixed. Unable to use diskwarrior as SSD is formatted as AFSP. Swapped the internal SSD with the External HDD, and was able to boot from the SSD while inside the USB enclosure. Similarly, I’m also able to boot from the HDD while inside the macbook. Ive tried running disk first aid and theres no problem. have also tried changing startup disk to no avail. What could be the issue? TL;DR: I have issues booting my mabook pro with a SSD. SSD inside macbook pro: No boot SSD inside external enclosure & USB: Yes boot Old HDD inside macbook pro: Yes boot Old HDD inside external enclosure & USB: Yes boot Thanks so much in advance!
It is the issue with the internal SATA HDD flex cable connector. This Macbook Pro A1278 2012 models have this common problem. You need to buy a replacement part and change it.
