Watch died as I was saving my run - how to recover the file?

I had selected Save and Effort Level, as I was selecting from the How did you feel question, the watch shut down. There is a FIT file on my watch, but when I try to manually import it to Garmin Connect, it says it can't accept it. I have seen in these forums that other folks were able to clean up the file so it would upload. Any advice on how to do that?