TL;DR / Geek Summary:

• System restoration guide for iPhone 6 using i4Tools to recover from APT package manager crashes.
• High-level workflow covering DFU/Recovery entry, firmware selection, and “Smart Flash” execution.
• Warning on Apple’s firmware signing window; underscores the criticality of pre-emptive SHSH2 blobs backup for downgrade capabilities.

# Methods to Refresh iPhone Firmware

I created this tutorial because an APT package manager crash occurred after I installed a plugin post-jailbreak.

# The Mainline of This Tutorial Series

This article is part of a series. If you’re coming from a search engine, you might be interested in other tutorials in the main directory.

Write down the guide for iPhone 6 and iOS 12 system (jailbreak + optimization + IPA reverse engineering + APP downgrade + firmware flashing + full backup + personal IPA signing + jailbreak plugin recommendations + precautions + resource download)

# Step 1 - Download i4Tools

i4 download

# Step 2 - Install i4Tools

Click next until the icon below appears on your desktop or start menu, then open i4Tools.

# Step 3 - Connect iPhone 6

This step may involve whether your charger supports data transfer and whether the data interface is corroded.

Successful connection is shown below:

# Step 4 - Go to the Flashing Tab

1. Click “Smart Flash”.
2. Click “Download”.
3. Click “Flash Now”.

# Conclusion

Besides the latest firmware, you can also use older firmware, but this requires you to have backed up SHSH2 in advance. Apple officially doesn’t want you to downgrade your system because it increases the risk of jailbreaking. Therefore, you need to backup SHSH2 beforehand—specifically for the system version you can last jailbreak. This is because the jailbreakable version will be immediately replaced with the latest version after you flash your phone.

Flashing is also a way to wipe traces of a jailbroken phone.