Another vote for not fixable.
The best method I've used is to remove the FB, and re-attaching it after a leveling.
A cruder method, or if there's no separate FB is to defret, level it, and refret.
The last, but not least is the fret-leveling lethargytartare talked about, but that requires jumbo frets in most occasions.
All that is obviously general talk and moot in this case as a BO neck is very seldom repaired since the replacements are plentiful for most designs.