During starting up, I always get "fsck not done Root device is mounted read-only..." error. When I type "Exit", it continues starts normally.
1 Answer
If you are not holding down the s key while booting then your NVRAM has a flag set or the keyboard has failed and is signaling that the key is pressed.
Try disconnecting USB keyoard at boot or resetting the NVRAM so that the normal boot proceeds.
Should that not work, you'll have to proceed with an odd-ball article followed by the general "Mac fails to start" article: