I'd buy this one and turn it to 100 degrees to macerate, any above 100 and you kill bacteria. Then when cleaned of all rotten flesh, I'd wash bucket out good, pour in dawn soap, turn heat to 150 and degrease for a couple of days.

https://www.amazon.com/gp/product/B00OYEABGQ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I'd put this heater on the very bottom of a home depot bucket which is what I do. If you read through the thread, its going to smell like hell for 3 days. I am now swapping water at 3 days to cut odor down. Don't pour it out anywhere a dog could get it or you'll be doing a lot of baths.