lisat

My sister has a 1991 es300 and whenever the battery is disconnected, I always have to go through the steps and enter a 3-digit code. I can always get it to work pretty quickly, but this last time, she wanted to try it herself. She entered the code incorrectly 5 times and now the radio is completely locked. It does not show SEC or ERR or anything on the radio display. Does anyone know how to unlock or disable the anti-theft feature once it has been errored 5 times?