Help with WD External Drive

I have a mid 2012 MacBook Pro, running OS Sierra, 4GB RAM, 512GB HD.

I was using a 3TB Western Digital Elements external drive for Time Machine backups. I recently purchased a new (early 2020) MacBook Air, running OS Catalina, 8GB RAM, 256GB SSD. I attempted to use Migration Assistant to move my files, not realizing the new computer had a smaller HD (I simply hadn't looked when I ordered), and there was an error because there was not enough space. I mention this because the WD drive was hooked up to the MBP at the time, and I'm not sure if that is a factor.

After using Migration Assistant failed, I copied the files I needed over our network, so that was fine. However, when I next plugged the WD drive into the MBP, I received an error message saying it couldn't read the device. I clicked "Initialize" and went into Disk Utility. However, nothing has worked.

First Aid runs and reports no problems.

Erase runs but then ends with an operation failed notice, saying it cannot write to last block.

Restore gives a similar error.

Mount is grayed out.

Computer restarts and shutdowns have not helped.

When I click "Info" from Disk Utility, it reports that the enter 3TB capacity is used, and that is wrong. Last I checked, there was over 1TB free on the disk. I'd like to at least reformat the disk, but can't figure out how since I can't even read it for a file listing. Any help would be appreciated.