This Bible contradiction is from the Skeptic's Annotated Bible.
God killed him with an incurable bowel disease.
2 Maccabees 9:5-28 View context
The Lord the God of Israel ... struck him with an incurable and an invisible plague ... a dreadful pain in his bowels came upon him, and bitter torments of the inner parts. ... Worms swarmed out of the body of this man, and whilst he lived in sorrow and pain, his flesh fell off, and the filthiness of his smell was noisome ... no man could endure to carry [him], for the intolerable stench. Being admonished by the scourge of God, his pains increasing every moment. He himself could not now abide his own stench. ... Then this wicked man prayed to the Lord ... to obtain mercy. ... Yea also, that he would become a Jew himself, and would go through every place of the earth, and declare the power of God. But his pains not ceasing (for the just judgment of God was come upon him) .... Thus the murderer and blasphemer, being grievously struck ... died a miserable death.
He was scared to death by the Jews.
1 Maccabees 6:8-16 View context
When the king [Antiochus] heard these words ... he was struck with fear ... and fell sick for grief. ... And he remained there many days: for great grief came more and more and more upon him, and he made account that he should die. ... I remember the evils that I have done in Jerusalem. ... For this cause these evils have found me: and behold I perish with great grief in a strange land. ... So king Antiochus died.
He was smashed with stones as he entered the temple in Jerusalem. His head was cut off and his body chopped into pieces.
2 Maccabees 1:16-17 View context
When Antiochus was come in: and opening a secret entrance of the temple, they cast stones and slew the leader, and them that were with him, and hewed them in pieces, and cutting off their heads they threw them forth. Blessed be God in all things, who hath delivered up the wicked.