People often forget that customers only complain and become vocal when they are unsatisfied, angry, and disappointed. Ledger has sold millions of hardware wallets. I think I remember sources talking about 3-4 millions. Even if you find 100 complaints right now where customers talk about bricking their hardware during a firmware upgrade, that's like 0.003% from 3 million. Even if it's 1000 or 2000, it's still insignificant.
But if something like that happened to you, Ledger will replace your device for free even if it's no longer under warranty.
Right, it's something that happens in everything we manufacture. For example, when you make cars, millions get made successfully, but not every car is as reliable as another. There's certain defects during the manufacturing process, which is unavoidable. You look at a pair of shoes, and they'll be slightly different, whether or not that difference can compromise their function, but it could, potentially.
It's the same here, there's a margin for error where certain devices can or will brick. It could be anything, during the upgrade sequence it could be something like not having a heat sink, and the device goes above operating conditions, or anything really.
However, this somewhat extends to software as well, since not everyone uses the software as specified, or if downloading, you might have not downloaded it correctly, or part of it was corrupted, which when the hardware wallet is fed that, it doesn't know what to do with it, hence the bricked device.
If they offer a replacement service for free, you can't really get any better than that. As long as you have your seed setup, it should be fine.