Is it possible to properly disinfect a washing machine without hot water?

Every single guide online says to use bleach or peroxide AND hot water.

Why is hot water necessary if the bleach already kills germs?

Due to a water heater issue, the water only gets luke warm even on the hottest setting, so I don't really have access to water hot enough to have any disinfecting properties, but I need to disinfect the machine because some idiot put a dirty towel that was on the ground being stomped on with filthy shoes for years in the washing machine.

I've seen some people saying to keep boiling water with a kettle and pouring it into the washing machine, but won't that cause the washer to overflow once you turn it on and start the wash cycle?

This is driving me nuts. Advice would be appreciated.