On the analog keys it’s worth checking the LEDs above the keys (which shows which pitch is being played on a track). That’s the only thing not working on mine (which I’ve had for ages); one or two of the LED’s are dead (might be easy to fix, but to me it’s quite cosmetic so I haven’t even bothered investigating).
Just play each key on the keyboard and they should all light up. Otherwise I haven’t had any problems with pots or displays, but I haven’t toured with the thing or treated it badly.
Every time I turn it on and play it I’m surprised how good it sounds, which is weird because I had trouble getting it to sound “fat” or “warm” when I first got it. Now I have a couple of patches that are extremely bassy, fat, warm and analog sounding. Like always with Elektron gear they are journeys and take some investment.