I’ve just finished building my Prusa I3 bought from the Official Store. Its the new 1.75mm version.
When I turn on the power on the PSU, the LCD panel lights up and displays 2 horizontal rows of black rectangles with a blank line between them and thats it. Nothing else is displayed and nothing else happens (ie no fans start and there is no movement.). I’ve double checked the LCD cables and they seem to be correct as per the build manual at manual.prusa3d.com.