Ask HN: How to fail fast in startup world?

There was a post in twitter where a guy created 8 startups in 8 days, out of which 2 startups worked and he spent more time on that afterwards. What is the framework for this? lets say if I have an idea of creating a hardware for a specific industry then what steps should I include and exclude to fail fast and validate?

I heard one strategy is to smoke test your product, where you just create a website and then validate from there. what are some others? any book, article , video if you think thats good. TIA