This firmware is not signed. This means you cannot restore to it in iTunes.
| Release Date | 22 January 2019 |
| Upload Date | 11 January 2019 |
| File Name | iPhone_4.0_64bit_12.1.3_16D39_Restore.ipsw |
| File Size | 2.87 GB |
| SHA256sum | |
| MD5sum | cb77d520c436221fa2bea9d0d8fb3e80 |
| SHA1sum | e57cc111d956cc553e3d3694944b6a40da7cfea6 |
| Identifier | iPhone6,1 |
cd ~/Downloads.idevicerestore -e iPhone_4.0_64bit_12.1.3_16D39_Restore.ipsw and press Enter.