I’ve used a truss rod rescue kit on a friends guitar with success.
As a carpenter I’d advise against trying to separate the fingerboard from the neck. It’ll be glued on, then pressed into place. You’ve got a pretty good chance of just destroying the fingerboard trying to separate the two. You could try steaming it to soften the glue bond but then you run into other issues such as unintentionally warping the neck.
If it’s already broken, then you have nothing to lose with the Stewmac route. Good luck. Pictures please, so we can all learn.