Wow, that's kind of scary.  If you figure out how to get his coins you should definitely have him reset his Ledger and write down his seed phrase.  As far as I know there's no way to display the seed phrase once the wallet is initiated.  That's by design, to maximize security.

On to trying to solve your situation without updating the firmware: you can try MEW: https://www.myetherwallet.com

On the other hand, I've never had to restore my hardware wallets after a firmware update, but I'd be very cautious doing that without exhausting every other option.  You can contact Ledger tech support and ask if they have a recommendation.