Allows selection of program, but will not start wash

A screw (from a pocket) got into drum, I had to remove & split drum to retrieve. Put all back together.

Machine now allows program selection, but when pressing 'start' button it does nothing. Door is locked during program selection which is not normal as it usually locks when wash program commences

I only removed wire harness to motor & heater so not much to put back(or get wrong). (all keyed)

*I've checked all wire connections across whole machine. nothing loose etc.
*water level pressure switch hoses are clear of gunk.
* double checked, triple checked

Any ideas please help

James