Not powering on - new keyboard

I have a Mid 2012 MBP on which I have replaced the keyboard as four keys were shot. However, having put it back together I find that it no longer powers on.

When I plug at the power adapter in I get the green indicator light and the battery charge lights operate as normal (i.e. come on, show charging and then go off - exactly the same as on the MBP I’m writing this on).

The power switch produces no results and I have tried the power pads also with zero effect. I haven’t tried pins 5 and 29 on the keyboard connector yet as I don’t think I have any thing I can short them and only them with.

Any other suggestions on what the problem may be?

Thanks

Laurie