If you cash the check it'll mean you have accepted a settlement and there won't be any court because settlements are enforceable.
If you want to take him to court, send the check back and sue him.
There's two possibilities:
1 - Read the TX security deposit statute starting with 92.102 at:
http://law.justia.com/codes/texas/20...-8/chapter-92/
If he hasn't followed the statute TO THE LETTER then you could be entitled to the entire security deposit back.
2 - He would only be entitled to the depreciated value of the carpet. If it really was 10 years old, he'd maybe be awarded only a couple of hundred towards it.

