Albert Barnes Commentary 2 Chronicles 30:15

"Then they killed the passover on the fourteenth [day] of the second month: and the priests and the Levites were ashamed, and sanctified themselves, and brought burnt-offerings into the house of Jehovah." — 2 Chronicles 30:15 (ASV)

The sluggish priests and Levites, who from a lack of zeal for worshiping Yahweh or from an actual inclination to idolatry had neglected to purify themselves (2 Chronicles 30:3 and marginal reference), were now shamed by the general enthusiasm and sanctified themselves for the Passover festival.

And brought in the burnt offerings - This means they received them from the offerers at the doors of the inner court and took them up to the bronze altar in front of the porch. No part of the burnt offerings was ever taken inside the temple building.