My harddrive failed SMART check and short drive self test. What should I do?

Back up everything you can from that drive, and then replace it. Short Test errors can sometimes be fixed, but SMART errors are usually permanent (an over-all SMART threshold for some error count has been exceeded).

Based on the information provided, I cannot tell you what is wrong, but you should certainly replace the drive if you care about anything on it. Your drive is predicting failure, so I would consider that a big problem.

You should also check to see if it is still under warranty. Depending on the drive, a 3-year or 5-year warranty would probably apply directly from Seagate if it is not OEM. Otherwise, you would need to contact the OEM for warranty replacement.