HOLY CRAP!!!!

So has anyone ever turned on the furnace and heard it trying to light only to find it didn't? I did! I followed the instructions and turned it off. I then turned the thermostat back on per the instructions. The fan came on and then POP! Very loud!!!! Fan stayed on, but no heat or any more noises that it was trying to light. Had a burnt smell after.
Any ideas as to what happened?

Ahhhh, the beauty of a helpfull fiancee...Robin had taped of the furnace vents when we winterized. She heard me talking about it and how spiders could get in there and mess up the lines. She saw that I missed that when I winterized. She taped them to help. I didnt know and tried to fire it up when we were getting ready to shower.
I think it was a backfire or sorts. Works fine, but there is a burning rubber odor. It blew the tape off the vents which is how I found out.
Awesome.....