This firmware is not signed. This means you cannot restore to it in iTunes.
| Release Date | 28 January 2020 |
| Upload Date | 22 January 2020 |
| File Name | iPhone_4.0_64bit_13.3.1_17D50_Restore.ipsw |
| File Size | 3.42 GB |
| SHA256sum | 1a729516c86546519890e0e286b9e6efe77f956a5096df0bea066b651b663141 |
| MD5sum | ee2df9b7791f4e7e45d20118288fdf53 |
| SHA1sum | ad73324ce0782b7ee78a5108c077666b2a73bb2d |
| Identifier | iPhone8,4 |
cd ~/Downloads.idevicerestore -e iPhone_4.0_64bit_13.3.1_17D50_Restore.ipsw and press Enter.