How to create decaying NFT? NFT can be decayed by burning the NFT after the expiry date has passed. Set the corresponding product expiry date on Token Creation. On Validating the warranty callafunction on smart contract that passes token ownership to address i.e. burns it.

How to tie NFT based warranty to physical product? By associatinganew ERC721 token with the NFT image uploaded for a particular product. Upload the NFT image on IPFS using Pinata. Using the IPFS url,we should createanew ERC721 token. Now return the new tokenID and store it in the database corresponding to the specific product.

How to transfer the ownership of the NFTs. By using the inbuilt transfer function of ERC721 token only when the transfer request is made by the current owner of the token. First type of transfer is done by using safe_mint function(inbuilt function)that transfers the ownership from Baddress to current owner's address. Second type of transfer is done upon resale,where the owner manually types the address to which it wants to transfer the ownership to.

How to track the repair and replacement to the original item? Wheneverarepair is done,the company can update the repair log. Before the repair,the customer needs to prove it's ownership. After the repairaUI is given for the company repairer to update the repair log database with the date and report of the repair to the corresponding tokenID.

How to prove the ownership of a product? Whenever the validate function on smart contract is called it checks if message sender's address is equal to the owner's address or not. Firstly, when the ownership is transferred then the metadata(NFT name, NFT Description,NFT image url)is mailed to the new owner's email id. When anyone validates the warranty,then the validate function will only when the request sender is the owner of it and will be able to view nft based warranty.