Apple restricts iOS/iPadOS restoration to signed IPSW files only. An "unsigned" IPSW means Apple no longer validates installation of that iOS version. Free tools exist to bypass this, but they require specific hardware (checkm8漏洞) or saved blobs (SHSH2). No free tool can restore any unsigned IPSW to any device unconditionally.
Steps:
Tethered vs. Untethered: Some newer methods are "tethered," meaning the device must be connected to a computer to reboot if it ever turns off. unsigned ipsw restore tool free
Successful restoration of unsigned firmware typically requires SHSH Blobs No free tool can restore any unsigned IPSW
Requirement: You must have previously saved SHSH2 blobs for the specific version you want to install. unsigned ipsw restore tool free
FutureRestore: The most widely recognized free tool for manual restores of unsigned firmware using saved blobs.
Step 3: Launch iRemovalPro (free version).