Hi,
When we renovated the kitchen 10 years ago our builders installed laminate floating floorboards over concrete (that use to have tiles).
They used plywood to level the floor... the floor now feels hollow in few places.
Some boards have moved and one sunk...


Wondering what can be done to repair this floor?
Is something like what is suggested in the video possible ? will it work ?
https://www.youtube.com/watch?v=7M5o1N3WdkI
Thank you for your help and advice!