Beginner: Left and Right analog and D-pad not working

So I have been inspired to repair broken stuff that I find online. and I bought this PS Vita that completely works except for the D-pad and both analogs as said on the item description. I still don’t have it as it’s currently being shipped as of writing this.

Is there a way for me to check which is broken the logic board or the buttons themselves? I don’t want to overspend and buy ahead both board and analog since I felt that I jumped the gun on buying this