TDS & Refund for Sale of Property by NRI

Hello Sir/Madam

My brother, who is a NRI, is planning to sell his apartment, which he purchased in 2006. The buyer informed him that the TDS would be deducted at 20% since he couldn't produce the LDC/Form 13.

My question.

1. Can the entire 20% + cess be claimed back if the capital gain is Nill?
2. if so, should he wait until the end of FY to submit the refund and how long will the refund process take?

PS: He doesn't have any other income in India.

Pls help clarify the above questions. Thanks a ton.