[Engine] Possible another dead bsi

[Damosmithy]

Hi im new to the birlingo but it ticks every box for me and the kids .The problem started when the belt went on my 04 1.6 16v petrol 110bhp model and not goving up with her i managed to get hold of a donor engine so i dropped it in and kept all the sensors and manifold ect from the the old one just incase it didnt like the new one .Only to find out when i went to turn it over thats all it did with no lights are horn or radio .I got a guy to see if it had lost the key code and he said it wont even read the key are eccept a new one so my question is .Will it be the bsi ? Can just get the same bsi of ebay are does any one recommend some one that really fix it without taking a up front just to say its broken .