Power off hook up to a charger and plug into your pc must have i tunes installed power off the device hold the power and home button into dfu mode and restore it through apple. It is not an android it does not reset with the method you are attempting. Good luck with your attempts! We fight for the right to repair and we must not eat e-waste for dinner in foreign countries. Hold the home button while the iPhone is plugged into the computer, then turn on the iPhone but keep holding the home button. It should go onto the recovery mode screen. Select restore from iTunes or 3Utools. Looks like firmware is bricked and needs to be restored, not updated.
If you did screw the cable up that renders home button functionality due to apples touch id security. However, You take the phone to a local apple store if your button does not work when you plug it back in. Good luck on your repair.
Over time a devices battery will die or drop to 0% if it goes under you will need to recharge them with a special board. I have seen this behavior on an iphone se charge it and see if it charger take precautions though battery may be acid leaking like a AA does in cold weather or when it gets old. Hope you find this response helpful. I’m 15 so im not the smartest thing on here.
So this sounds like an issue with the lcd flex cable get someone that is trusted in this field to look at it cables are very very fragile especially the ones that samsung use in their watches and galaxy s models.