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Installed Mac OS Catalina in my Samsung SSD internal drive used as an external device. It is able to boot my MBP as an external hard drive but when I put it as an internal hard drive it is not able to boot. When I go to recovery mode and check the disk utility the internal hard drive is not even showing up. Please help.
Often I find the HD SATA cable is either bad or the older version which won’t run the drive at the higher SATA III (6..0 Gb/s) data rate the system can support. Apple used older SATA II (3.0 Gb/s) HDD’s and the SATA III (6.0 Gb/s) HDD’s don’t tend to push the cable as hard as an SSD can! I would replace the cable MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable and here’s the guide MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement. Make sure you don’t crease the cable as sharp bends damage the thin foil wires within it. I use an old BIC pen ink straw as a forming brake curling the cable around it where the cable needs to be bent. Don’t exceed the radius of the straw for the bend. Lastly, if you already replaced the cable then give this a try with the SSD installed: Restart your system and press the Option (⌥) key to enter into the Startup Manager, now select your SSD from the listing using the arrow keys. The system should finish starting up, if it does go into your preference settings and alter the Startup Disk to your new drive. References: Your Hard Drive Cable Is A Ticking Time BombMac startup key combinations
