The rules are interesting. If the EC doesn’t do the job....then the House and Senate get their assignments. The Senate will take the top two candidates for VP, and each senator gets one vote each. Pence wins in this case.
For the House, they must vote as a state delegation...one vote per state. They will get the top three candidates, which will include Johnson (not Stein).
There are three states with an even number of Republicans and Democrats, so toss them to the side. Thirty-two states have a Republican lead. This vote should take no more than an hour of meeting together in one room and counting the House member votes and assigning your state to one single person. 26 votes are all that are necessary....so Trump easily wins.
Odds of Johnson getting into this mix? Zero. Stein, sub-zero.