They come in, reduce costs as much as possible, keep revenue coming in as long as they can while having huge dividends to said PE until they get so far into debt they are not sustainable. They'll swap to service providers that they either own or get a cut from and pay themselves.

Then their purchased company gets bankrupted, sells their assets to cover their debts (including said PE's 'debts' of services provided.)

They probably make 200-300% of their initial investment back by paying for the initial purchase with debt that is tacked onto the purchased organization and simply drain them dry. PE doesn't make a ton of money by being dumb, they make a ton of money using any and all tactics necessary to make big stacks in short time. Obviously not all PEs operate like this and there are likely many loopholes and strategies.

They bankrupt it by basically pumping it full of debt while taking money out and dumping it once it's out of money - zero liability with a LLC right?