A quick glance online leads me to believe that your unit uses a spark ignition. If it uses a spark igniter you need to clean the pilot, related, wiring and check the gap. Most now use the same wire that sends the spark out from the ignition module to also sense the pilot flame. If the probe or ceramic base or wire gets all sooted up it can give a dielectric value that is incorrect and the ignition module will consider this a flame loss or out of range value. if the gas control module senses flame loss it will run another ignition sequence and repeat for a set number of retries. After a certain number of ignition trials or if it senses a flame failure a certain number of times the ignition module locks out. Cutting power to the ignition module unlocks it and the whole cycle starts over.
Ignition modules come with all kinds of start and lockout parameters. Check your service book or inside the cover panel for the correct information.
Look for the ignition module and follow the often orange high temp type wire to the pilot. They most often look like a gray 3"X5" plastic box with 4 or 5 wires and sometimes a green LED. Clean everything and check that the tip of the ignition spark probe is the correct distance. Rough is 1/8 or so.
Another issue that comes up is the pilot assembly often has a port that clogs up. Pilot flame gets smaller and smaller until it causes the flame sensor to think the pilot has blown out. This port is right around where the tube fits into the pilot assembly. remove the tube from the pilot and look inside you should see a thimble shaped metal insert with a small hole. I run some wire brush wire through it. Be careful not to distort or enlarge the hole.
Another thing to check for is overheat. If the air intake screed gets clogged up it might be overheating and cutting out on high temp. Most high temp safeties are manual reset but this is worht checking considering that the unit is in a body shop.