Seagate External Drive will NOT erase and is now invisible in Finder

I used the following to format my 8TB Seagate drive. My drive, although it mounted at first, when I tried to erase it using Disk Utility, it failed and then no longer would mount at all. I opened Terminal and issued the "diskutil list" command and saw (also noted from research online) that it had a Microsoft Reserved partition which is what causes it to fail to erase using Disk Utility:

/dev/disk3 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *8.0 TB disk3

1: Microsoft Reserved 134.2 MB disk3s1

2: Apple_HFS 8.0 TB disk3s2

I issued the following command and it erased and mounted and was erasable in Disk Utility:

diskutil partitionDisk /dev/disk3 1 GPT HFS+ newdisk R

-Scott

I had the problem too, for Seagate 5Tb, did help be to use the step by step procedure with small change :sudo dd if=/dev/zero of=/dev/rdisk2 bs=5120 count=5120! It worked, after may days of searching for the solution this was the only one working! THANK YOU

Ive done it all so far and it seems to be working well, but when i get to the password stage instead of what you wrote:

You’ll see something close to this when done:
Password:

1024+0 records in

1024+0 records out

1048576 bytes transferred in 0.890086 secs (1178062 bytes/sec)

It instead says:

Password: "and has a symbol of a key here"

and it doesn't let me type anything afterwards

Id appreciate it if you could help, because i have no idea how to fix it

Thanks!

First you wanna identify the name of the disk. You know how to do this. Open Terminal and type:

diskutil list

Rad!
Look for that external hard drive or USB drive that is being a jerk. Find out if it's disk2, disk3, or whatever.
Next, you gotta get this disk to UNMOUNT. Let's enter this next line into Terminal;

diskutil unmountDisk force disk2

Of course, “disk2” is what the name of MY current device is, but it may be different for you. Check that ‘diskutil list’ list.
However, for now, you should be seeing
“Forced unmount of all volumes on disk2 was successful”
That’s how ya know ya done did it!
*Spoken with a southern twang*

Next, we need to remind this disk who we are, and not to f**kin play games with us! We are the bosses here! This ain't Terminator 2, Judgment Day (yet)!
We ‘bout to write zero’s to this disk, and nuke this b**ch!
(Translation: We are zeroing out the data on the disk.)

sudo dd if=/dev/zero of=/dev/rdisk2 bs=1024 count=1024

Hey!
Do not forget to replace the rdisk2 before pressing the Enter.
Then enter your password when asked to.
You’ll see something close to this when done:
Password:

1024+0 records in

1024+0 records out

1048576 bytes transferred in 0.890086 secs (1178062 bytes/sec)
Dawg,

You’re going to Hollywood!
We are almost there.
For this next step; Remember to change ‘disk2’ to what ever you have as a name for your disk. AND! we need to change “MediaDrive” to what ever name you want your drive to have.
Let’s now try to partition the disk. This will be the HFS+ format:

diskutil partitionDisk disk2 GPT JHFS+ “MediaDrive” 0g

Hooray!!! The Disaster is over!
But don’t forget to change from HFS+ format to APFS format using Disk Utility, bruh!

Had this problem, too and you walked me through this with great ease. I'm a fan forever. Thank you for your time in helping us out here!

Beezermigs, appreciate your helping me solve this issue. God Bless You!

Thanks Beezermigs - that worked. Legend.

Been fighting with this since a horrible episode with Parallels. THANK YOU!

You sir... are the sheit.

thank you!!!!, it works now!

When you originally tried to format the drive, did you choose Erase or Partition?