Brand new external hard drive formatted exFAT is mounted read only I bought a new HDD, formatted as exFAT with mac.
I moved files from my laptop to the HDD (moved, I mean, I also deleted them).
It happened with a directory it got stucked. I quit the process of copying that directory.
I tried to trash and erase trash. I could not erase it.
I tried eject from Finder. It could not.
I unplugged - when there were no process active.

I tried to plug, and could not mount.
I discover apple run fsck automatically. I kill the process, used diskutil to mount the volume, unmount and eject.

I tried to plug and mount and again.
Now the volume is mounted, but Read only. 
S.M.A.R.T. not verified.

So I launch fsck - I don't know when it will finish, there are (estimated) about million files, HDD is 4T.

I m confident disk is ok, since brand new.

Please advice on how get rid of read-only and steps to mount exFAT external HDD properly in mac, want to prevent automatic fsck - also because fsck is taking forever, and not sure it could repare anything if in read-only mode. 
FSCK is stuck at checking system hierarchy:

    diskutil list

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            499.4 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:       Microsoft Basic Data myHDD                 4.0 TB     disk1s2



sudo fsck_exfat /dev/disk1s2
fsck_exfat: Opened /dev/rdisk1s2 read-only
** Checking volume.
** Checking main boot region.
** Checking system files.
** Volume name is luigi4T.
** Checking upper case translation table.
** Checking file system hierarchy.




Mac OS 1.9.5
If your exfat drive shows up as read-only, then all you need to do is unmount the drive and then use the "mount_exfat" utility to mount the drive. Once you do this, and right click on the drive → "Get Info" will tell that you have custom access to the drive, instead of "read-only". Here are the steps:


Open the terminal on your mac.
Type diskutil list and you will get a listing like this:

/dev/disk0 (internal, physical):    #:                       TYPE NAME SIZE       IDENTIFIER    0:      GUID_partition_scheme                
*500.3 GB   disk0    1:                        EFI EFI                     209.7 MB   disk0s1    2:                 Apple_APFS Container disk1         500.1 GB   disk0s2

/dev/disk1 (synthesized):    #:                       TYPE NAME        SIZE       IDENTIFIER    0:      APFS Container Scheme -              
+500.1 GB   disk1
                             Physical Store disk0s2    1:                APFS Volume Untitled - Data         407.2 GB   disk1s1    2:           APFS Volume Preboot                 82.4 MB    disk1s2    3:           APFS Volume Recovery                528.5 MB   disk1s3    4:           APFS Volume VM                      3.2 GB     disk1s4    5:           APFS Volume Untitled                10.7 GB    disk1s5

/dev/disk2 (external, physical):    #:                       TYPE NAME SIZE       IDENTIFIER    0:      GUID_partition_scheme                
*5.0 TB     disk2    1:                        EFI EFI                     209.7 MB   disk2s1    2:       Microsoft Basic Data Backup Plus             5.0 TB     disk2s2

In the listing above, we notice that /dev/disk2s2 is our external drive. Unmount the drive by runningsudo umount /dev/disk2s2`.
Now create a directory in in /Volumes by running sudo mkdir -p /Volumes/&lt;name of your volume&gt;
Mount the hard drive to this directory your created by running sudo mount_exfat /dev/disk2s2 /Volumes/&lt;name of your volume&gt;.


Once this is done, you should be able to create new folders and write to your drive.