If you send it back to Seagate you will loose the data. No you don't need a receipt to send it back, and if you open up the drive, I think you will void the warranty.
Here is the link if you want to get a new drive under warranty. You have to pay to ship it to them. They will ship it back for free
https://store.seagate.com/webapp/wcs...=SgSSORedirect
Are you able to see if the drive is missed up our the external encloser that is messed up?
Good luck.