IDK if I would feel comfortable using a mobile device as a cold wallet. I think simply speaking mobile devices are too volatile and susceptible to crashing to be good enough to serve as a cold wallet. From what I can see from the OP it looks like if the screen of your cold wallet were to be cracked to the point that a camera cannot read a QR code displayed on it then you would not be able to sign transactions with it (I guess you could technically sign them, but you would have no way of getting the TX onto the network without connecting it to the internet). Another concern is how frequent it is that people will steal phones, and the number of reasons people have to steal your phone. If someone were to steal your cold wallet phone then you would essentially lose your private keys, regardless if the thief is able to steal your money or not.
Actually mobile devices like iPhone or Android phones are not too easy to crash. The manufactures like Apple, Samsung, Moto are following higher industry standards to provide stable devices for people's daily use. Also because you should keep your Bither Cold Wallet phone in much safer environments, for example in your home but not in your pocket, it will be much safer.
Bither Cold also supports two kinds of backups:
1. You can easily clone the Cold Wallet private keys on a new phone, the only thing you need to do is scan the clone QR Codes.
2. With many Android phones supporting SD cards, you can buy some SD Cards, Bither cold will automatically backup encrypted private keys on SD card.
Bither also support advanced options for private key managements, you can backup the private keys in your own way.
Thanks for your support,
A car has run over my phone. Its screen has been broken. And it still works well as a cold wallet. Here is a photo of my phone.
