Worse, it means you may need a new 4-in-1. If your tail motor still works, try reversing the two motor connections to see if your main motor works when connected to the tail motor plug. If it does and your tail motor doesn't work when connected to the main motor plug, the problem is in your 4-in-1. If you're very handy with a soldering iron and you can get the correct MOSFET, you may be able to repair your 4-in-1 if it's not too burned up.

-JT