If there is no will then you can't have it spread of record. Likewise, you should know that the POA is nullified at the moment of death of the principal. It is however relevant if you seek to be appointed Personal Representative of his Estate. However that may not be necessary.
There is a small estate affidavit procedure that you could use but you will have to hire a lawyer to draft it for you. Probably one in the county where your brother was domiciled who holds out experience in probate and estates would be the best choice.