Response
You should send a legal notice to the buyer stating that the Apple Airpods purchased by him through OLX were of best quality and they checked the product thoroughly and was satisfied with the quality of the product before buying it.
The buyer will be considered as a consumer under section 2 (7) of the Consumer Protection Act, 2019 and the agreement of sale that occured between you and the consumer is a valid contract as neither of you were forced to buy the product and there was free consent from both of you.
As the buyer had checked the product before agreeing to buy, even if he sues you in the Consumer Court, you have a defense, you will need to keep the receipt of the payment for the product, any of the conversation between you and the buyer regarding the terms of refund, exchange or return.
If the terms of the purchase stated that the product cannot be returned, the consumer will not be able to claim damages or get a refund for the product.
If the buyer continues to threaten to file a complaint against you, you can file a complaint against them under section 506 of the Indian Penal Code, 1860 and the buyer can be punished with an imprisonment which may be extended upto two years or be fined or face both the punishments.
Reference: 1. Consumer Protection Act, 2019
Section 2 (7) Consumer
2. Indian Penal Code, 1860
section 506 Punishment for Criminal Intimidation – 202100289-20210004-827 –
LAWAYZ-2023-501