DIY carpet cleaning Tips?

TLDR: Can't afford professional carpet cleaning, and looking to get the odor of male dog urine out of carpet.

Hello y'all. My girlfriend and I adopted a dog around Christmas last year (2024), and since then we have been doing our damndest to get him house trained, but he is six years old and has definitely lived a pretty different life than he is now. We've tried shampooing and doing everything in our own power to get the smell out of the carpet but we cannot do it, and when getting professional cleaning quotes it's just way out of our price range. Does anyone have any tips aside from professional services or just tearing the carpet out?