By booting your iPhone into DFU mode and then attempting a software recovery, you should be able to get it working again. This solution necessitates the use of a computer, so be sure you have one. Also, make sure you have the most recent version of iTunes installed. If you're ready, take these steps to perform a DFU recovery:

1. Close all active apps on your PC.
2. Launch iTunes.
3. Turn your iPhone off. If you can't switch it off properly, deplete the battery to 0% and the phone will shut down on its own. Without attempting to turn it on, charge the phone for at least one hour.
4. Use a USB cord to connect your iPhone to your computer.
5. Press and hold the Power button for at least 3 seconds.
6. While holding the Power button,press and hold the Volume Down button on the left side of the iPhone. Hold down the Power and Volume Down buttons for ten seconds. Repeat steps 5 and 6 if the Apple logo shows at this point. The Apple logo should not be displayed at all.
7. Hold the Volume Down key down for another 5 seconds. Repeat steps 5-7 if the Plug into iTunes screen appears. The screen that appears when you plug in your device to iTunes should not appear.
8. If the screen on your phone remains dark, you're in DFU mode. After that, your computer should inform you that an iPhone has been discovered by iTunes.
9. To complete a full recovery, follow the on-screen instructions on your computer.

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