How do I reset my Genie intellicode wall mounted garage door opener?

Please help! Kids forgot their house keys so they were locked out in 29 degree weather after school. Against his better judgment, my husband gave my son the code for the remote on the outside of the house to open the garage door.( If it wasn't so cold, we would have made them wait until we could get home to let them in the house).Somehow they have totally messed it up and it does not work at all. I tried to use the reset instructions I found online for the Genie remote, but it does not seem to work. Can anyone give a suggestion? I first tried to reset the thing by holding the cover halfway and pressing the PROG and 8 at the same time then opening the cover fully. Close the cover. Open the cover again fully and press 357, then PROG and then enter your CODE and then press PROG again. Close the cover. I tried this several times and it still does not work. HELP!!!!!!