This firmware is not signed. This means you cannot restore to it in iTunes.
| Release Date | 12 January 2022 |
| Upload Date | 08 January 2022 |
| File Name | iPhone_4.0_64bit_15.2.1_19C63_Restore.ipsw |
| File Size | 5.03 GB |
| SHA256sum | 5ec386cdd86a0901f6e3f02f8dfd6f382db8708dd462bcfd29bd822f38bced67 |
| MD5sum | ed8be5f886367d9ba002021d58ace544 |
| SHA1sum | 1c0e359e765c9e899bad246268755f5a61de43ed |
| Identifier | iPhone8,4 |
cd ~/Downloads.idevicerestore -e iPhone_4.0_64bit_15.2.1_19C63_Restore.ipsw and press Enter.