Dryer was running with full load of clothes. Heard a loud pop twice, ran back to the laundry room and smelled like something burning. Turned dryer off, and now it won't start back. Also, the very top of the dryer is extremely hot.

bad or broken belt, not sure if its ever been serviced ?
bad drum bearing, bad drum teflon pads or both possibly
or both possibly or in combination the belt could need replacing

Its never a good idea to leave a clothes dryer unattended. They are often a source of house fires. Is it a gas dryer? Maybe a gas leak, do not use until checked by a qualified person. If electric tumble dryer, then maybe the smell was caused by some lint collected around the heater element, and it eventually scorches and stinks like that. Either way,get it checked by a profession qualified person, don't risk a fire in your house! Hope this helps, good luck.

Sounds like the motor went out. Before trying to start it it needs to be inspected. If you are not comfortable opening up the cabinet then I would would recommend calling a service tech. If you need further assistance please let me know.
Ken

Does the sewer drain line have a trap at the bottom that prevents sewer gas from entering the room? If the smell seems to be coming from the washer itself, run a wash cycle empty with a cup of baking soda, detergent and hot water to clean the interior.

sounds like the motor unless something is stuck in the blower housing such as a sock

When I had the back off of the dryer I did notice one thing that looked a little unusual. The vent
pipe, which the flame of the burner travels through, ( running from the burner to the back of the
dryer ) was painted, inside and out. Some of the paint was cracked and slightly bubbled, as though
it was melting from heat, and there actually was a small pile of soot laying there. I wiped off as much
of the paint as I could with a rag, and vacuumed it out, and put the dryer back together and ran it.
After running the dryer for a while we no longer have the smell. I don't really know if that was the problem
or not, but at least the smell is gone.

you can unplug the unit , and reomve the lower aces panel (3 screws along the front bottom of unit) youll probalby see an excess of lint built up in which case you can vacuum it out, and then check/clean and or replace your dryer vent

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try taking a flashlight and look over the back of the drier see if the vent got mashed or is all coled up and stuff let me know also you can remove the vent from the back of the drier and run 1 load to see if it works normal if so then you know the vents the culprit.

you need to clean out you venting ...it is most likely clogged or filling up