Try a high quality cold chisel and 5 to 8 pound hammer and chisel the hinge bracket off the door and the frame of the safe. Once done, the door will hopefully pry open from the hinge side.
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Sentry safes are garbage, look online for ways to break in. some only need a sharp hit on the top of the safe while gently turning the handle, some can simple use nail clipper file or bobby pin to easily pick the key.
I haven't read all posts.....A drill bit, a sawsaw, and go in the back or bottom. If you can't get in the door.
You can get in with a partner saw with a fiber or concrete blade pretty quick too.
There are tons of ways if you don't care about the safe. We found a safe years ago dumped in a strip mine pond, Drug it through a mile of woods, worked for 8 hours trying to get it open after we finally got it home....We were sure there was something in there!!!!!!!.....We found 55 cents in change....