Some iPhone users experience problems with Pangu jailbreak released by Chinese hackers. This tool supports iOS 7.1 and 7.1.x smartphones and tablets, but it can cause iPhone 4 boot loop issue which can be solved using this guide.
The problem comes when you try to restart your smartphone. Though not all users get across reboot loop bug, it still happens to some people who probably wish to fix Pangu boot loop on iPhone 4 as quickly as possible.
The fix is simple and there is nothing to worry about here. Maybe the solution looks crazy but it has helped some people and can solve your issue as well. So far the Apple logo appeared after Pangu jailbreak on the iPhone, however some other models might also suffer from it.
How to Fix iPhone Boot Loop Apple Logo
This Pangu jailbreak fix is weird but it works for a lot of users. Hackers updated their iOS 7.1.x tool with the fix in it. You can download the latest version of Pangu for Windows or Mac and perform jailbreak without boot loop issue.
The jailbreak steps are easy and you can follow detailed tutorial guide to jailbreak iOS 7.1.x with Pangu. After completing and rebooting you will see Cydia on the Home screen and not Apple boot logo.
The problem is noticed to be related to the Ambient Light Sensor (ALS) which causes your gadget to go into boot loop if you restart it in the darkness. You need some light and brightness to avoid this issue, and there will be no problem at all. Just restart your handset under a lamp or in the sunlight and you will not experience boot loop problem after Pangu jailbreak.
Ambient Light sensor is a indicator that can figure out how much light can be found in the location around the iPhone, iPod touch, and iPad and immediately change the illumination of the display that allows you to preserve life of the battery.
This sounds weird and crazy but as this Pangu boot loop fix works for some users it might also work for you.
Personally I would recommend to update with newer iOS 7.1.2 so the Pangu 1.1.0 version is able to fix this issue.