iPhone stuck in DFU mode, update/restore not working
My iPhone 6 was working fine before today, but this morning it entered DFU mode, and I haven't been able how to figure out how to unlock it. I tried using iTunes to update it, but Error 9 occurred. The same thing happened when I tried to restore it. Also, when I try to update/restore it, my iPhone goes to a black screen for a second, then to the apple logo with a loading bar under it, then quickly goes back to the DFU screen with a lightening cable and a iTunes logo above it.
It seems like Error 9 is about the connection to iPhone/laptop, but I have tried different cables, different USB ports, and cleaning out both the port in the iPhone and laptop. The cables I used work for charging and uploading pictures,when I used them yesterday, so I am pretty sure it is not the cable problem.
When I hold the power button on my iPhone, it turns off, then goes to the apple logo for a second, then back to the DFU screen. I have also tried holding power button and home button for 15 seconds, as well as several other random things I saw on the internet.
What do what should I do to get out of DFU mode?
iPhone 6