The Electors at the Electoral College decide. Depending on how they decide, the House can select a President, and the Senate a Vice President.
Slates of Electors are sent to the Electoral College based upon whether their candidate won their state.
They don’t go to an “Electoral College.” They go to their state’s capitol to cast the vote.
Think about this. What if Hillary has blackmailed or threatened an elector? What if she has an elector whacked on the way to the state capitol and has bribed an alternate?