Revelation 12:8

they did not prevail
Prevail is ἴσχυσεν [ischysen] , indicating that the dragon and his angels had insufficient power to withstand Michael and his angels. The elect angels of God are able to defeat the most mighty of the fallen angels, including Satan (Rev. Rev. 20:2+). Christ does not even condescend to participate in the conflict, for like all the angels, Satan is a creature, albeit a powerful one. Many people have the completely cockeyed view that the Bible concerns a battle between Satan and Christ. Nothing could be further from the truth, because Satan himself is a creature of Christ’s creating (Col. Col. 1:16). The gap between Creator and creature is inestimable. Christ could merely blink and Satan and all evil would instantly and permanently be vanquished. Yet he withholds their doom for His purposes, only a tiny corner of which He reveals to us—much of it in this book. For Christ, as God, to stoop to battle directly with the devil would be providing Satan with a great compliment. Hence, he is dealt with by Michael or other angelic powers, who are themselves creatures.

nor was a place found
The woman had a place prepared for her to which she fled, but the dragon no longer has a place in heaven.

any longer
Prior to this battle with Michael, the dragon had access to heaven as he does in our day. See commentary on Revelation 12:10. See commentary on Revelation 20:2.