Fret buzz as a beginner

[lvrossem]

My first ever bass guitar (Ibanez GSR200B) just came in, and it came with some significant fret buzz/rattling on the top 4 frets. Possible fixes I've read go from "just give the truss rod nut a quarter turn" to "get some advanced measuring equipent and measure this and this and that" Any idea what kind of measurements these are? I assume it's related to the exact distance between strings and frets, which is specific per fret or sth? In any case, I've already found that all the frets are the same height using a credit card