Performed diagnostic on 2018 trane system. Homeowner states system is not turning on at all. Tried cycling system for cooling, system is unresponsive. Went into attic and inspected indoor unit electrical and system components. Found a broken fuse at circuit board. Checked wiring and circuit board for any sign of a short, did not find anything concerning. Homeowner states he did remove thermostat from the wall to replace his batteries. This could have caused the fuse to break. Replaced fuse, system kicked on and started cooling. Filters are both dirty and should be replaced. Checked outdoor unit electrical and system components. All look to be in order, secondary motor control is in range. Outdoor condenser is very dirty with dust as well as pet hair. Strongly recommended having maintenance done on system. Refrigerant pressures are in range and system is producing proper temperature split. Went over findings and recommendations with homeowner. Only wants to take care of immediate fix fo