What did Hezekiah do in the first month of his reign?

Answer: Reopened the temple doors

Ahaz had shut the doors of the LORD's house; in his first month Hezekiah opened and repaired them.

“Then Ahaz gathered up the articles of the house of God, cut them into pieces, shut the doors of the house of the LORD, and set up altars of his own on every street corner in Jerusalem. In the first month of the first year of his reign, Hezekiah opened and repaired the doors of the house of the LORD.”— 2 Chronicles 28:24, 29:3 (BSB)