After dissasembling a Canon MV600i the unit will...

Question

I needed to repair a canon MV600i camcorder with a new board. I did this and after re attaching the ribbon cables and other cables all carefully as not to break them the unit would not power up again. At first i thought it could be a faulty spare board but it did the same when i switched the old board back. I havent missed anything obviouse that i know so where am i going wrong??? Any help would be amazing or a service manual if anyone has one.Cheers