If your GC can’t read miniDVDs correctly (DiskReadError always) read this guide to solve the problem.
Open your GameCube and remove the laser. You can see the laser is holder with a pcb.
Turn the pcb to find a small pot. With a digital multimeter (see image below) turn the pot counterclockwise until you measure 200Ohm.
The value must be between 170-210 Ohm but never 250Ohm and above.