I haven't finished my 50 state and 50 state stars quilt that I have done with crayola crayons yet. However I did use cotton and put a paper towel on the ironing board, placed a paper towel on top of the picture "face up" used hottest cotton setting with NO Steam and pressed for about 5-10 sec. in each spot until I could smell it - not too long or it will scorch. You can tell by the feel of the block when it has worked it seems. If this washes out I will be just furious. I have worked too long and too hard on this quilt.
You might try going to crayon quilts on the internet and see if you can come up with a site that gives you info on doing a crayon quilt. I did, but sorry I can't remember the name of the site just now.
Sorry you had problems with this. Keep us posted on the outcome.