VCS VideoJet X.21 Manual page 70

Advanced Features
Once reprogramming is complete, the green LED will stop blinking.
F
Any attempt to upload an invalid firmware file will result in receiving
the message <upload failed>.
F
Once firmware has been successfully uploaded, revisiting the page
"General settings" yields the version number of the new firmware
appears.
72
VideoJet X.21/G.703
Manual