Electronic potting materials experts..........Holley EFI

I was given a "mostly dead" Holley Dominator EFI computer, and am attempting to depot the thing. Rather than some soft pliable potting material, this stuff is like.............JB weld.

I'd LIKE to get into it without destructing the electronics "very much." Thinking of steam, boiling water, baking in oven, etc? Ideas?

What you see here are some very rough cuts with a fly cutter in the old mill drill. A great amount of the top of the case has not been milled away, and the header on the connector row was broken loose and bent up and just broken off