Try disconnect the battery and leave it off for a few min and then reconnect?
By any chance did you accidentally touch the positive and negative together at some point?
That's very strange
Are there any panels on the dash that have the buttons unplugged?
For example, I know if my hazard warning light button was unplugged in a another car I own, the indicators wouldn't work
There are a few HKers here, but not sure how active they are, if you do a search you should find a few :)
Would be awesome if you all identified each other and done a meet up since HK is soo small, would be cool to know the local owners
If your wastegate is closing fine by itself, then you've probably got something else wrong with regulating - maybe the sensor that is used to check the boost pressure is giving incorrect data back to the ECU.
Also are you sure you don't have any leaks anywhere?
Hey! Welcome to the club!
We've got a number of US members situated in Japan at the moment, even a youtuber too @Jitsu-no-Jeff
Here's his channel :)
https://www.youtube.com/channel/UCsa_mLbfKD8Fp0WDnJKNUeg