Tell him to restore the wallet from the seed or import the private key into another wallet like Electrum. If it's a bug on blockchain.info not displaying his balance, that should let him spend his funds. He should have control over that address because he has previously sent funds from it, so it's not like a bug where b.info gave him an address without having the private key.


It's easy to use, gives you access to your private keys/seed unlike an exchange or most web wallets, and is fairly popular. It's also the second result on google if you search "bitcoin wallet".


Electrum isn't a hardware wallet because it's fully software. A hardware wallet is a Trezor, a Ledger, and whatever other physical products there are.