Can I replace the insulation in an LG oven?
I've done this (due to rat pee (which is at least as bad as it sounds)).  It is a straightforward DIY job, just be sure you have good screw management solution.  I prefer to tape screws near the hole they came from.

Just get thin unfaced fiberglass batts in the right size. Remember that many call fiberglass the new asbestos, and wear a minimum P100 mask and non-fabric gloves.

You can also try running an "oven cleaning" cycle and cook the corpse to carbon black.  If it's just a corpse you have a good chance the smell will dissipate, at least if the corpse is really right against the oven wall.

See also How do I replace oven insulation that has been soiled by mice and smells bad?