Water damage on 2 years old laminate floor

[Hui Kiang]

Hi all,

I noticed the floor in one bedroom is buckling and warping on edge after the tenant moved out. I texted the tenants and she said their family didn't do it. They requested coming over this weekend to check it out. How should I handle the situation? I'm not interested in keeping their deposit but I do want them to have someone fixes it. If they can't, I will find a handyman to do the repair. 

We did a thorough walkthrough before she moved in and videotaped it. There was no floor damage. Unfortunately, I only kept the youtube version and the quality is too low to tell the condition of the floor. We also did final walkthrough 2 weeks before she moved out. But the area was covered with furniture. At the day she moved out, they were in a rush and I kicked myself so hard for not doing one final detail walkthrough when the floor is finally clear. 

If they still insist they didn't cause the damage, can I still deduct the cost of repair from her deposit? How would you handle it? Thanks in advance.