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How to determine $O(L)$ is finite or not?

Let $L$ be an indefinite {\it non-unimodular} integral lattice. I am particularly interested in unimodular cases, such as $U(2)\oplus A_4, U\oplus D_4$. Are there any general method to determine whether or not the orthogonal group $O(L)$ is a finite group?

I am aware of this similar question Automorphism groups of indefinite non-unimodular integer lattices The difference is, I am interested only in whether or not $O(L)$ is finite.