The court shall not accept a plea of admission of the facts from the minor without first determining that it is made voluntarily, with awareness of the nature of the alleged offense and of the consequences of said plea. Furthermore, the court shall warn the minor regarding:
(a) His right to be represented by counsel during all stages of the procedure and that, if he lacks the economic means, the court shall appoint one to represent him.
(b) His right to be presumed innocent, until proven to the contrary, and to have the Prosecutor prove the alleged facts beyond any reasonable doubt.
(c) His right not to declare on the stand, and to have witnesses for his defense subpoenaed.