Again, there is zero use in an iOS device being carried in DFU mode. All that will do is waste battery, because the single function of DFU mode is to wait for the USB interrupt started by a computer sending a Apple-signed bootloader to use to boostrap loading of the firmware restore RAM disk.
As previously mentioned, it seems that you have the idea that DFU is a "mode" that you can boot iOS into. This is absolutely not the case, the device screen is completely black and the device appears to be completely off, because it almost is, it's just "spinning" and waiting for the USB interrupt.
The reason I am very adamant about this is because your comment was upvoted when the advice would serve no purpose to someone who needed it.
If you do not believe the device will reboot, go get an iPhone now and boot into DFU mode while plugged in. Then look at your computer and wait for it to recognize the DFU connected device (only way to know when it's in DFU versus being off). Then unplug it and watch, it will reboot into normal iOS at some point (or power itself off if battery is low, depends, same point though).
As previously mentioned, it seems that you have the idea that DFU is a "mode" that you can boot iOS into. This is absolutely not the case, the device screen is completely black and the device appears to be completely off, because it almost is, it's just "spinning" and waiting for the USB interrupt.
The reason I am very adamant about this is because your comment was upvoted when the advice would serve no purpose to someone who needed it.
If you do not believe the device will reboot, go get an iPhone now and boot into DFU mode while plugged in. Then look at your computer and wait for it to recognize the DFU connected device (only way to know when it's in DFU versus being off). Then unplug it and watch, it will reboot into normal iOS at some point (or power itself off if battery is low, depends, same point though).