All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
What your brother did is pure Riba so he should repent from it and ask Allah to forgive him. He should also pay back this loan without interest if the company accepts that, otherwise he should pay it back with its interests and never do any more similar transactions.
Please read Fatwa: 81378 and 82049.
Your brother can also buy this machinery through Muraabahah (the company buys this machinery from its seller then sells it to this man by installments adding some profit to the price according to the period the installments will take). But the amount they add to the price of the commodity should be fixed and not a percentage related to possible delays in payment.
Allah knows best.