I'm surprised you can get the parts for it, I spose at that money some will repair them.
Maybe if you powered a strip then flexed it around with a 'driver and see if you can find an open in the board, on a board that isnt lighting if you set your power supply to current limit you could short out each led with a pair of bird beaks, when you get to the bad one the rest should light, assuming no more than one is bad.
If you replace any leds, colour temp match might ne an issue, maybe not so bad for just one or two.