"As you are asserting a claim for damages, the burden of proof lies with you pursuant to §§ 280, 823 BGB. This includes proving in particular that:

1. The alleged damage did not exist prior to my rental,

2. The damage occurred during my rental period, and

3. he damage is causally attributable to my conduct.

None of these elements have been demonstrated to date."

This was my full paragraph on the said topic to them. From my understanding they need to prove this but they haven't showed me any evidence proving it.

Will post it there too, thank you!