What is the test for a defendant who waives his right to represent himself in court?

Appellant, who had no prior criminal record, appeared for the first time in a criminal court at his arraignment on the criminal complaint on January 27, 1995. The court advised appellant of his right to counsel and appointed the public defender to represent him. On March 14, appellant filled out a form waiving his right to counsel and requesting that he be allowed to represent himself. However, during voir dire on appellant's right to self-representation, he changed his mind and requested substitute counsel under People v. Marsden (1970) 2 Cal.3d 118, 84 Cal.Rptr. 156, 465 P.2d 44 (Marsden).