Maybe they didn't clean the lint trap.  Or, the hose that comes out of the back of the dryer had lint build up, restricting air to escape, creating heat.  Very important to clean lint trap.  Check and clean BEFORE you put clothes in to dry.  Heat from dryer can burn the accumulated lint.  Happened before.  Just pull out the lint trap from the top or inside the dryer, depending on the brand, and remove the lint.  Only takes a couple of minutes to clean it.  We have 4 people in our house, so, quite a bit of laundry every week.  I clean out a handful of lint every time.  Better safe, than sorry.  Hope the ohana can fix the damage.  Glad no one was hurt.