Welcome to the ebike world (of addiction) Toolboy.
In addition to the above comments, be sure to check that your brake levers are adjusted properly. Many, if not most, ebike power systems employ a power "kill switch" circuit that is activated whenever the brakes are applied (i.e. brake or brakes on = throttle off). If the brake lever(s) and/or brakes are adjusted wrong the system will not throttle up.
Good luck with your latest project and let us know how you get on with it!