Albert Barnes Commentary 2 Chronicles 22:9

"And he sought Ahaziah, and they caught him (now he was hiding in Samaria), and they brought him to Jehu, and slew him; and they buried him, for they said, He is the son of Jehoshaphat, who sought Jehovah with all his heart. And the house of Ahaziah had no power to hold the kingdom." — 2 Chronicles 22:9 (ASV)

Compare the marginal reference. After remaining for a while at Megiddo, Ahaziah moved to Samaria, where his wounds could be better cared for and concealment might be easier. Jehu’s emissaries discovered him there; they took him to Jehu, who happened to be at Megiddo at the time; and then and there Jehu put him to death. This narrative is therefore supplementary to the one in 2 Kings and finds its proper place between the clause “He fled to Megiddo” and the words “and died there.”

And when they had slain him, they buried him — Jehu’s emissaries killed him but allowed his servants to bury him (see 2 Kings 9:28).

No power... — As Ahaziah was only twenty-three at his death (see the note on 2 Chronicles 22:2), he had no grown-up son to take the crown.