SanDisk Extreme Portable SSD V2 500gb

Last Christmas I bought the disk for my sis, which she barely used, and recently she told me that it’s not working. Tried my best, but nothing there. Using the terminal, I was able to see the disk but was not able to access it. On Windows, I see it, but I also cannot access.

This was supposed to be a bulletproof disk, but it is a huge failure, it seems.