I installed BiteSMS (for iOS 7) by accident. And my iPhone got stuck in the infamous reboot loop. You will notice your phone reboot, and you will see Apple logo, and eventually after 60 seconds it will reboot again and so on. Here are suggested solutions that I have attempted:
1. Hard Reset – Holding power and home button. Result: same Apple reboot cycle.
2. ReiBoot – Excellent software that lets you Enter and Exit Recovery mode. Result: same Apple reboot cycle.
I was running out of ideas. Then I read somewhere that you can by-pass Cydia substrate by holding Volume UP until you actually see your phones lock screen. Result: SUCCESS
Once I was in, I was able to get into Cydia, and I unstainstalled BiteSMS. Then I held the power button and shutdown and rebooted thereafter. All was back to normal.
I hope this helps someone who wants to preserve their jailbreak. This was performed on iOS 9.0.2.