Prusa I3 pro B: issues with the board ?

[Soadyheid]

Hi,
The "E" or extruder motor does not work quite like the X,Y and Z motors, it has an electrical interlock. It will not be enabled until both the hot bed and extruder temperatures are reached. This prevents operation until the filament in the extruder has been melted and is able to be, er..., extruded. I have drawn a small line with a sharpie on the visible end of the extruder motor shaft (RH end) so that when it is turning I have an indication.
Hopefully this is what's happening with your setup, it's not a fault, it's a safeguard. The cold filament would just get chewed up by the feed cog if the motor was allowed to turn though I reckon the motor would just stall first, maybe damaging the electronics.

Play Bonny!

Soadyheid