In Melachim II, 9:27 it says that that Achazyahu fled via Beis ha'Gan. Here it says that he hid in Shomron, and they brought him to Yehu, and killed him there!
Refer to Melachim II, 9:27:1:1-4 and the note there.
In Melachim II, 9:28 it says that that they buried Achazyahu in Yerushalayim. Here it says that they brought him to Yehu, and they killed him, and buried him [there], "for he is Ben Yehoshafat." Surely Yehu was not in Yerushalayim!
Radak, Malbim: They killed him in Yizre'el, and they let Achazyahu's servants take him to Yerushalayim to bury him there.
Why does it say "v'Ein l'Veis Achazyahu Latzor Ko'ach l'Mamlachah"?
Malbim: There was no heir to inherit the kingship and rule. The children of Achazyahu's brothers, the descendants or Yehoram and Asalyah, Yehu killed them. I explained in Melachim that Yehudah never consented to Achazyahu's kingship; only Yoshvei Yerushalayim made him king. This is why his army did not save him from Yehu! Therefore Asalyah seized power for herself.
