It has been a while
Just go to mission planner were I assume is where you messed things up, go to the parameters screen and click load, there are a bunch of stocks in there look for x8 or octaquad. or you could just load the firmware for an octaquad on it. Mine is no longer a 3DR X8 as I moved it from the old frame. But Before and Now I just use the stock octoquad parameters and it works pretty good right out of the box, then do auto tune if you want