Do I have to download a custom ROM?

[AC Question]

Earlier today, my galaxy s6 got over-heated, and turned itself off. Afterwards, it wouldn't restart normaly, so I decided to power it back up by pressing, and holding down volume down + power button + home button. I was then greeted by a lightblue screen, saying "Warning
A custom OS can cause critical problems in phone and installed applications. If you want to download a custom OS, press the volume up key.
Otherwise, press the volume down key to cancel."

If I press the volume down key, nothing happens. If I press the volume up key, there comes up a screen saying "Downloading… Do not turn off target.", along with some information about the device in the upper left corner + "Odin mode" I decided to leave the phone on this screen for three to four hours. When I came back, nothing had changed. This seems like the only thing I can do with the device at the moment.

So my question is, what do I have to do to make my phone work normaly again, and is it necesary to factory reset it? And if it is, is there any way I can save some of my old files and data? Thank you.

 

[Golfdriver97]

Welcome to the forums. You can restart the phone by pressing power and home I think. This simulates a battery pull.

If the phone doesn't work after that, you may need to consider flashing a stock ROM.