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I’m having an issue with macbook air. It doesn’t boot up when internal drive is connected. When I take out the internal drive and boot from external drive, the machine works fine but when the internal drive is connected I can’t even boot from the external. Please I need your help on fixing this.
Sounds like the boot sector of the internal drive is corrupted.Try using another computer to download ubuntu to a usb stick.Google this to follow the instructions.What you need is Gparted which is a version of Partition Magic. Then Go to the machine you have trouble starting and try to alter the boot sequence to USB from startup.No need to install linux, just run it from USB and let Gparted …you may need to disconnect the internal drive and load the usb linux first.Then reconnect drive and rescan drives using Gparted.It shoukd allow you to read the files and correct boot record. It is possible to copy the contents to another drive and or correct the boot sector.I wouls save any files BEFORE changing or correcting the drive.There are other tests you can run to see if the drive is failing of full of bad sectors. I have also done this on a windows machine.Also you cam use Hirens boot disc.Again google, download Hirens to USB and connect the internal drive via correct leads to the windows machine.Start USB first, load Linux Gparted.. This is enough to run a chkdsk and correct boot sectors and MFT….as well as copy clone files. Need further help , i will try to help.
So lets work out the issues you are facing here. When your boot drive messes up you can face a few different issues trying to recover things. The first one is trying to boot up under an external drive here we need to get to the Startup Manager within your systems firmware to select the alternate drive. Hold the Option (⌥) key then you can select your external drive without removing your internal drive! Reference: Mac startup key combinations OK, how to fix your internal drive with your external drive now the boot drive run Disk Utility to check it out under First Aid. Did you get any errors? You might want to run it a second time to be sure you got all of the errors. Do make sure you’ve using the same OS version on your external as Apple has changed the file system under High Sierra & Mojave to APFS from HFS+. Older Sierra and back boot drives won’t have the ability to see this newer file system. How full is your drive?? If you don’t have much free space you’ll want to copy off anything you can to free up 1/4 of the drive. I would also take the time to make a backup to be safe. Then we want to re-install the OS running the OS installer using the same OS your system is running. If you don’t have it you can get a fresh copy from the Apps Store looking at the Purchased listing for it. What I like to do is make an OS installed USB thumb drive How to create a bootable macOS Sierra installer drive
