Do you need the data off the drive?
If not, just go to Seagate's web site, fill out a Return Merchandise Authorization form (RMA), and it will give you an RMA number. Ship it back to Seagate and they'll send you another drive.
If you need the data, do not RMA the drive to Seagate -- they will not fix it and send the same drive back to you. Basically, there's 4 ways you can go:
1. Professional data recovery. Likely to be expensive, although not as bad as someone with a drive that needs to go to the clean room.
2. You can attempt to superglue the part back together, get a SATA cable on it, and then copy the data off if you're successful. (If you need to, superglue a cable in place as well. You'll sacrifice a cable, but get your data back.)
3. Swap the electronics board of your HD with an identical one from another HD of the same model. (Pretty easy solution if you have another HD available).
4. Remove the electronics board, cut a SATA cable, and solder the SATA cabe leads onto the board bypassing the connector. (Difficult, requires soldering skill and equipment. But possible.)