My turbo had all the tell tale signs of a dead turbo: play wit actuator rod and chattering sound when let go off gas, winding sound when boosting up at 3000rpm in cold weather, and no boost! I am reading zero boost. I replaced all vac hoses and TT BV last year, and they were checked with no problems. I am pretty sure I will need a K04, but what else should I check so I don't miss anything. Like the N75. How do I check it? I want to do everything in one shot and not leave anything dehind.

I scanned it but no error came up.

You may want to check the wastegate to see if the rod is broken or disconnected. That's not uncommon on older 1.8T's.