The judge assigned may consider the motion solely upon the affidavits, but may, in the exercise of discretion, convene an evidentiary hearing. After consideration of the evidence, the judge assigned shall rule on the merits of the motion and shall make written findings and conclusions. If the motion is sustained, the selection of another judge to hear the case shall follow the same procedure as established in Rule 25.4 above. Any determination of disqualification shall not be competent evidence in any other case or proceedings.