If the power indicator light is illuminated, potential causes for the keyboard display issue may include: 

     1. Damage or short circuit in the power supply board;

     2. Poor connectivity of the keyboard cable;

     3. Damage to the main control board. 

  If the power indicator light is not illuminated, possible reasons for this failure could be:

     1. Absence of input power;

     2. A broken fuse;

     3. Damaged rectifier bridge.