farm land pawned

Good day! I wanted to ask legal advice about the farm land of my deceased grandfather. My mother pawned it 30 years ago amounting to 4000 with my grandfather's authorization letter & the land's title copy (not sure if it is Original or photocopy) but without any agreement with regards to the term of the loan and interest rate. She pawned it to a friend's friend. My grandfather gave "rice" -once or twice as part of the payment for the debt but i think it wasn't fully paid. In short, the debt is unsettled. Since then we never heard anything to the person who lent the money nor approach us to pay the debt. Now, my mother's siblings wanted to sell the land to have their shares. We have the Original copy of the title plus our family is still paying the tax so I HOPE there will be no problem in selling it. But one of my mother's brother is threatening her and he is always making trouble to her because he said that they can't sell the land because it was pawned by her. Would it be possible that we will have a problem if we sell it? What about if the person who lent the money have also the Original copy of the title? Does she has the authority to take the land? And if in case we wanted to settle the debt how much do you think it would cost us? My mother is really scared that it would cost her so much to pay the debt because when she asked her friend about it she said that it was already 100k 10 years ago so she told us that for sure she can't settle it anymore now and scared that the person she owes might have interest on the rice farm if in case she will approach her. Please help enlighten us, thanks.