Chosen Solution
I repaired an apple watch myself, but I used a full digitizer/LCD unit. Although you probably tried this already, when I firstly reassembled my apple watch, touch wasn’t working either, but only because the connector wasn’t connected properly, although I was convinced I had it connected correctly. Maybe checking this could help you out.
I have the same issue and ordered a new digitizer to replace it, Did you ever find a fix? Apple wants to charge $200
