Polar 92x - keyboard not connected

Trying to troubleshoot this error.
On startup, it freezes with No keyboard connected on screen.
Cleaned all ports/connections.
Attached photo

Thks

 

Hi :
1) Test the power supply High voltage +5Vdc+24Vdc :a) if there are in tolerance b) or is missings
2) See if the ribbon or flat cables are good, Replaces.
3) Test inverter for Hight tension for Display.
Use the wiring diagram or schematic diagram