When your iPhone is stuck in boot loop status, there are 3 methods you can try:
1. Try to force restart your device to see whether it works. Just press and hold the Power and Home button on your iPhone 4s simultaneously for about 13 seconds. You will feel your iPhone vibrating, then it will automatically break the boot loop process.
2. Restore your device with iTunes. This is another way to break the boot loop status which is to rely on iTunes to restore your iPhone. Just connect your device to the computer, go to the Summary > Restore iPhone and confirm the actions. Wait for the process to complete.
3. Use a third-party iOS system restore software to fix it. Using iTunes to restore your iPhone will erase all the data on your device. If you don't want any data loss, you can try an iTunes alternative to fix your iPhone stuck in boot loop with ease. Just connect your device to the computer, choose a repair mode, download the firmware package and start to repair it. Done.
See more: How to Fix iPhone Stuck in Boot Loop