To restore iPhone when the device has a software error, you usually use iTunes to manipulate it, but 3uTools application has the same iPhone restore feature as iTunes, the operation is much simpler.
Note: This is a 3rd party application so you should consider carefully when manipulating. During the restore process, you must not unplug the cable, do not turn off 3uTools. In addition, you need to exit your iCloud account before doing so to avoid unexpected situations.