Fitted new mother board and heat mat and it does not printsad smiley

Hello, first post!

I am quite new to 3D printers so please bear with me and my question.

I have a Reprap Mendel 3DP03 3D Printer.

A while ago the heat bed malfunctioned and caused one of the cables to burn damaging the connoctor between the main bored and power supply

So I have fitted a new mother board and heat mat but the printer just will not print a single thing, I have checked the levelling, the extruder, the software and nothing will get it printing.

Please, does anybody have any idea what the problem could be here??

Thank you in advance!