1. In order to prevent the regret of upgrading ios7, first use AISI Assistant-Advanced Player-Backup SHSH from the device. 6. 1SHSH will be automatically uploaded to AISI server after backup, and can be downgraded at any time in the future.
2. Then use PP assistant to back up the important data in the device! ! ! ! Download the firmware of iphone4 6. 1.3, open iTunes, hold down the keyboard shift and click Restore to find the downloaded 6. 1.3 restore (your device has escaped from prison, so updating ios7 directly will fail, so upgrade 6. 1.3 first and then upgrade ios7).
3. download ios7beta2/read-htm-tid-6542935.html.
Open iTunes, hold down the keyboard shift and click "Update" (Note! Yes, click Update! Don't click "Restore", otherwise it can't be activated). Find the downloaded ios7 beta 2 and click OK to upgrade ios7.
If you are not satisfied with the experience of ios7, you can use "Aisi Assistant" and "One-click Brush" to downgrade to 6. 1.