Small Diagnostics: is the gas line open, does the dryer still operate (tumble) but it does not heat, does the exhaust blow air out if so then the gas delivery, motor, vacuum motor are possibly working properly.
website http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5170716&diagram_id=28476104#d28476104
Issues might then be in the ducting or the heating unit, this is the schematic of the gas line, heating, and ducting within the core of the dryer: If you take a close look at number 16 which can be seen inside the tumbler, Sometimes the port/ matrix of small air vent can clog up due to lint. Make sure that vent is not blocked. This prevent hot air from coming into tumbler.
When a unit over heats or fails it could be related to the high limit thermostat which is a sensor that get tripped or blows when it reached its limit check and see if its fried/ burnt (number 17).
Diagram number 2: http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5170716&diagram_id=28476105#d28476105
This one contains or blown out thermostat fuses check and see if they are OK on diagram 2, Part number 8 Tstat and 10 thermal fuse.
Hopefully this help.