cannot access USB-attached hard drive (also it's not responding after firmware update)

I have a WD 16 TB My Cloud Mirror Gen 2. I just recently tried for the first time to attach a hard drive (also a WD) to one of the two USB ports in the back, but it does not seem to be accessible. When I attach the hard drive directly to the computer, I see that it works fine.

Also, I saw that the firmware update was available, and so I tried to update it. But now the My Cloud Mirror is just showing the flashing blue light. It’s been like that for a few days now (it said it would need time to index the files again after the update, but it said it would only take minutes, not days), and I cannot access the My Cloud Mirror at all now, ever since I started the update process. I wanted to try to reset or turn it off and on, but I wasn’t sure if that would be safe.

If anyone has any ideas on either of these issues, it would be greatly appreciated.

Hello,

Please be informed that External USB drives file system format must be FAT32, NTFS or HSF+ and in some cases exFAT.

Refer to the following KBA article: Configuring USB Backups on a WD My Cloud

In order for the My Cloud OS 5 mobile and web app to access data stored in your My Cloud NAS, the device needs to index the data first.

https://support-en.wd.com/app/answers/detail/a_id/30021/

Thank you for your response.

The new hard drive is in NTFS format. I reformatted it, even though it was brand new, just in case (after reading the suggestions I found elsewhere on this forum).

As for the indexing, should that be taking over a week? When it said that it would need to be indexed again after the reboot, it said it would take minutes, not days.

I looked through the two links you referenced. In the second one it says that it is safe to reboot the device while the indexing is still going on, and it will not need to restart indexing from the beginning again. I may try to do that.

After the 40 second reset (4 second reset didn’t do anything), now it’s a solid red light instead of the flashing blue light - and I still can’t access the Mycloud Mirror at all.