If your warranty is still valid, return it to the shop and let them send it to an Arturia service point. To me it seems you have a first generation keybed. Do you see blobs of glue beneath your keys? That's an indication it's a first generation. The keys are be prone to becoming detached from their weights, because the glue isn't powerful enough.
I also had this problem with my Keylab25, and I let it be taken care of. The entire keybed was replaced by a different type that is more reliable (no visible glue beneath the keys).
If you send it for repair, have some alternative to play with meanwhile, because your Keylab won't be back within a few weeks. It may take as long as two months.