PIC12 - ADC never returning zero

[Doomkeks]

Just a side note on this topic. I stumbled upon it by googling my problem during my mayhem today:

I got into PIC ADC for the first time today, also with the PIC12F1572. Programming in XC8 C, also for the first time.

No matter what I did, the ADC always read about 0.4V too low. At the same time it was fluctuating quite a bit without touching anything. I thought I did some stupid rookie mistake.
I was trying all kind of power supplies, ways of coding, voltage references and what not for a whole day. As a last ditch, I swapped out the PIC for a different identical one.
Aaaand yep, that was it. I had a faulty PIC.
I wish I tried this earlier. So keep that in mind.