**If want to navigate easily, can plug in a USB Mouse to navigate the on screen menus, without using touch screen.
Check
Settings
System Vers/Info
Press and hold Information Box - Keypad will come up 7890 ok
System
Set Screen Origin to Positive
Set Touch Origin to Positive
Reset unit by either pressing the RST button with paper clip
or turning car off (wait 10 seconds) then turn car on to see if settings have been set