The Board of Review shall hold a meeting on the Monday following the date of its first session, and, at that meeting, shall complete the review of the assessment roll submitted to it by the Assessor and shall endorse and approve the same as provided and required by law. The omission of such endorsement shall not affect the validity of such assessment roll. If, for any cause, a quorum of the Board of Review does not assemble, or in the event that the Board fails or refuses to act during the days set for the meeting thereof, the roll as prepared by the Assessor shall stand as if approved by the Board of Review, without further formality. After the review of the assessment roll has been completed and the roll endorsed and signed, as required by law, the Board of Review shall redeliver the roll to the Assessor.