Soaking in acetone (at least a day) will usually soften the epoxy, just enough to be able to pick away at it but there will be a lot of manual work involved. Unfortunately it will also soften and damage some parts like the shrink wrap on electrolytic capacitors, epoxy coated disc capacitors, etc.
There are some stronger, much nastier solvents that will do a better job, not sure if any of those will actually liquefy the epoxy though, and they are not commonly available. Very likely to also damage some other stuff of course.