Cannot delete files or format MicroSD card

I have a 2 GB SanDisk MicroSD card.

I normally use this card in my Nikon camera but ever since I used it in a Brother printer, I cannot delete any of the files, write or format the card.

I've searched online, including SuperUser, but my problem seems unique in that I do not get any errors when deleting, writing or formatting card.

Nikon Camera: Everything appears normal when using this card taking pictures… no errors when supposedly saving the photo. However, when trying to view pictures, the camera reports that none can be found. I can do a "Quick Format" within the camera'a Setup screens but the card is not formatted and no errors reported.

Brother Printer: Scanning direct to this MicroSD card. (this is the incident that "broke" the card) First document scanned fine. Every subsequent attempt since then always gives an "Out of Memory" error.

MacBook: I am manually deleting the files without errors, but the next time I insert the card, the files re-appear.

SDFormatter: I downloaded and installed the latest version of SDFormatter (v4.0 Mac) from sdcard.org. I am doing a "Overwrite Format" option, I get no errors, and the format completes with a success message. However, all of the original files remain on the card!

I am using a MicroSD to USB adapter with the MacBook and a MicroSD to SD card adapter with the Nikon.

Clearly, based on all observations above, I cannot write to the card. Weirdly, with the exception of the Brother, I just don't get any errors when writing.

It's like the card is locked, even though it cannot be locked without the hardware lock on the SD adapter, and I never get any "write protection" errors.

I suspect that a corrupted MicroSD card is the root problem, but here are my questions:

1. Why would I not get any errors when writing, deleting or formatting?

2. What can I do or use to verify the hardware integrity and/or fix this card as needed?