This firmware is not signed. This means you cannot restore to it in iTunes.
| Release Date | 26 January 2022 |
| Upload Date | 23 January 2022 |
| File Name | iPhone_4.0_64bit_15.3_19D50_Restore.ipsw |
| File Size | 5.04 GB |
| SHA256sum | 57e5d20201b0d1b4238b620f69541bcec7733be07d5952681518a71f93203307 |
| MD5sum | e46ab1893056b01c050289a210408d00 |
| SHA1sum | cfa06a22d3748c8f4fd85903bcbc9d5a6f84e56e |
| Identifier | iPhone8,4 |
cd ~/Downloads.idevicerestore -e iPhone_4.0_64bit_15.3_19D50_Restore.ipsw and press Enter.