With the terminal turned off:

1. Simultaneously press the power key and the down arrow key
2. The screen will show a "SYSTEM MODE" menu. 
3. Use the arrow keys to navigate to the "INFO VERSION", which should already be highlighted.
4. Press the green key to select it.
5. Use the down arrow key to scroll the information until you see the entry marked "OPA". 
6. Below this heading, you will see the entry "AP VER", alongside which a version number will be displayed, for example "1.3.0.3". 

This is the Software version number of the payment application running on your terminal.

To return the terminal to normal functionality:

1. Press the power key to turn off the terminal.
2. You can then turn on the terminal as normal.

If you have any further questions on this topic please do not hesitate to contact our support team.