Sounds like your wallet was "double encrypted" from the very beginning with a 2nd password

There is another option to test... which would be this:
https://github.com/blockchain/my-wallet-backup-decryption-toolYou can setup that tool on your local PC and try and decrypt the wallet.aes.json file just using your main password. See if that works... if it doesn't, then it is almost 100% guaranteed that your wallet has the 2nd password set and you'll need to try bruteforce it with btcrecover.