Answer:
Opal Koboi was defeated as she was tricked by Artemis Fowl and team by secretly sending Mulch Diggums to steal the charges and hides it into Opals secret compartment purposely so that Opal and the Brill brothers think Artemis has it so they try to blow it but she escapes into the surface in a woman's grape farm where her magic fails to mesmerize her and she is stuck there to work till the LEP come to fetch her in prison.
hope this answer clears the doubt