I put some BTC on an old bitcoin core wallet which was on an external USB drive back in 2015. I then encrypted and locked it with a password. I now want to retrieve the coins but when I attached the drive to my current laptop, I am seeing zero balance and no transaction history. I spent about a week downloading the entire blockchain again, now up to date but it is still showing zero.

However, the password I noted is not working and the wallet is locked. Should the bitcoin core wallet show the balance when the wallet is locked, or do I need to put in the password first? I thought the password was only required to send. I really want to see the balance, so that if there is something there (I really thought there was, and if it's empty why would I have locked it in the first place).

I can't export the private key without the passphrase. I also tried the dumpwallet keys.txt command in the console but unfortunately I get met with:

Error: Please enter the wallet passphrase with walletpassphrase first. (code -13)

I'm assuming that as the wallet.dat has been moved to a new client, it wont show me anything at all until I unlock the wallet.

Before I start launching into btcrecovery to try and crack my own password, is there any way I can see my balance or any public keys from the wallet.dat ? I would rather not go through it all and then find the balance really is zero.

thanks for any help