I assume you’ve don’t this before and the Synology uses a disk format that Mac can read?

Not much you can do after it’s been storage. Boot it up. It will work or it wont.

You need to perform a low level format to get all of the bad sectors marked. After that, you can partition and perform a normal format. When that is complete, if it still shows as bad in CrystalDickInfo, I wouldn’t trust it.