Legal Question in Real Estate Law in California

Someone needs to petiton to administer the will and estate. Only that person can do anything about the situation and only once they are approved to administer the estate by the court. Since you are contesting the will, you cannot be the administrator.

What powers are granted by the power of attorney? It may be sufficient for you to bring an action called "ejectment" which is the usual kind of lawsuit to get rid of trespassers. However, your power of attorney would have to be fairly broad. Your brother who gave you the POA may have a sufficient right to possession of the property, pending the outcome of probate, to eject squatter/trespassers with no right at all. It isn't clear from your question whether it is you, or one or more of the brothers, who is contesting the will. Nor is it clear whether the estate is in probate, or whather the house passed under the terms of a trust, and so on. Houses are sufficiently valuable to make doing this right (i.e., using lawyers) worth while.