Damages Claim against Deposit

[Jeff A.]

We just received a notice from the apartment manager we moved out of that they are going to charge $900 against our secrutiy deposit because of a damaged front door, cleaning, and some other minor stuff. He says that we caused the front door to be damaged and he is going to replace the door for almost 700 bucks.Totally rediculous.
We didn't cause the damage but he is blaming us.
Can we fight this? We don't have money for a lawyer, is there anything we can do. This is not fair.
Any help would be apprciated.