I borrowed money from my brother for hajj before he died. Is my hajj valid? As I did not visit Medina during hajj, I would like to know whether it is valid?

Visiting Al-Medina
Your hajj is valid provided it fulfills its conditions and pillars which do not include visiting Al-Medina. Although it is not among the rites of hajj, it is recommended to visit Al-Medina because it is from the etiquettes of hajj and 'umra.

Validity of the hajj of an indebted person
The fact that you borrowed a sum of money from your brother which you have not yet repaid, does not invalidate your hajj. You must repay the money to your brother's heirs — his wife, children or others as the case might be. Each heir is to receive his legal share from the debt.
And God the Almighty knows best.