To solve the issue, you can try the process below :

Formatting the calculator:

Formatting the calculator:

1. Press and hold the <2nde> key.

2. While holding <2nde> key pressed, remove a battery and put it back; you will get a screen with the message "Waiting .... Install operating system now ''.

Then you have to process an update of the calculator : you can follow the process here (same process as the other calculators).