The mechanical drive has probably failed. If you put the iPod in a freezer bag and get it very cold, it may spin up long enough for you to make a backup. But make sure it is in a freezer bag or something otherwise airtight or the condensation will brick it worse. The cold shrinks the metal enough to mitigate the initial friction of the drive spinning up.
From there, you can mod it to work from a micro SD card.
From there, you can mod it to work from a micro SD card.