Hot water Issue! Overheated and then now hot water

[Kanwar Sodhi]

Hey guys, one of tenants said that while she was washing the dishes, the water over heated and now there's no hot water at all. Anyone with experience recommend what I should do next? I'm already on the phone trying to get my service guy to come out.

What can it be?

Past history:

1 Month ago: Tenant had complained about water not being hot enough and service guy had come and turned up the thermostat.