Thought I’d share this as it might be useful to other people.
I got a switch today that would only display when docked. Stripping the motherboard out I noticed the LCD connector had a few bad pins so I swapped that but still the same.
Next I inspected the board and found to 2 caps(?) near the Pi3USB to be snapped in half so I replaced those but still no LCD display.
I then spent a bit of time measuring around the Pi3USB but couldn’t find anything out of the ordinary so after looking at the Pi3USB datasheet I thought it might be a problem with the control of the Pi3USB IC and swapped out the cap(?) that is attached to pin 1 and that fixed the issue.
i probably spent 4 hours trying to figure this out so maybe this will be helpful to someone else. in the picture below 1 and 2 are the snapped caps and 3 is the cap that i replaced to bring the LCD back to life.