Then Baasha son of Ahijah of the house of Issachar conspired against Nadab, and Baasha struck him down at Gibbethon of the Philistines while Nadab and all Israel were besieging Gibbethon.
In the third year of Judah's King Asa, Baasha killed Nadab and reigned in his place.
When Baasha became king, he struck down the entire house of Jeroboam. He did not leave Jeroboam anyone alive until he had destroyed his family according to the word of the Lord He had spoken through His servant Ahijah the Shilonite.
References for 1 Kings 15:29
This was because of Jeroboam's sins he had committed and had caused Israel to commit in the provocation he had provoked the Lord God of Israel with.
The rest of the events of Nadab's [reign], along with all his accomplishments, are written about in the Historical Record of Israel's Kings.