Satan and the fallen angels cannot change because they are angels and angelic beings are pure spirits. Humans are embodied spirits, subject to the laws of created time, and so can change. Because of their purely spiritual nature and their superior intelligence, the angels made a definitive choice either for God or against him. Those who chose for God are in heaven with him; those who chose against God cast themselves into hell. The fallen angels cannot repent (just as the angels in heaven cannot now fall). This means that the fallen angels, including Satan, cannot repent, be saved, or go to heaven.
