Note that after you have spent a fortune on the new LCD kit and replaced it, the watch firmware may need to be reflashed or the watch will never pair again. As signed firmware is not available this could be a dead end. You’ll find many examples of failed repair attempts among the threads here.
Someone wrote that IOS12 might solve the problem, but I now installed the IOS12 beta 3 and tried to pair the series 2 watch. It did not help a bit - it was exactly the same error message that I have got all of the time since the display shift. Anyone tried WatchOS 5?
The same thing happened to me. If you look at the other questions on this forum, you’ll find two other examples of exactly the same problem. Unfortunately no one here seems to have a fix. On another forum I read that the watch has to be reprogrammed using IBUS S2, but this adapter + software costs a fortune (more than 100 USD each for adapter and software).
As far as I can see it is not only cosly to replace the screen on ones own, but also risky. You’ll also find examples in this Answers forum on persons who replaced the screen seemingly without problem but then never got the watch to work again. In my case the series 2 watch cannot pair to iPhone at all after the shift, and no one seem to be able to help us that get into trouble.
The exact same thing happened to me! Have you figured out how to solve it? I disassembled my watch again and reconnected the screen just in case it was connected wrong the first time, but it did not help. I am most thankful for help. Right now the watch is useless, which is frustrating considering the expensive replacement LCD.