@Anita-And-Bruce0 it is a tough situation for the host whenever you have to deal with something like this.
While there is no way to avoid the risk of unpleasantness, this kind of event highlights the advantage of a short, strictly factual, and newspaper-like review from the host. While a guest can take offense at any review, it is harder to argue that a strictly factual review is true. To wit:
"After (guest names) stay, we discovered that the button on the toilet flush system was broken off. The button was not broken before their check-in. No other people were in the unit after (guest names) and before our discovery of the broken button. "
Saying something like that is short, factual, and does not level any accusations at anyone. It just reports what happened. You don't have to talk about how disappointed you were, how you had to rush, what the guest should have done, etc.
Future hosts will know what you found. The guest will find slightly less material to be offended about.
The facts as stated are hard to dispute.
I hope the guest does not cause you any further unpleasantness!