iPhone stuck on red battery screen

You need to confirm that your phone is actually attempting to charge the battery—-to do that, use a usb ammeter. This tool will tell you if the phone is consuming charging current (and therefore charging) or not—then you have something you can troubleshoot. The *most common* reason an iPhone X is not charging is lint in the charge port—clean out with a toothpick. The *most common* reason an iPhone X is showing the Apple logo loop is a drop of water under the flood illuminator which is attached to the ear speaker assembly at the top of the screen (there’s a long flex from the top of the screen to the motherboard). You can disconnect that part and see if the phone will boot without it. Follow an iFixit guide for disassembling the phone—it is easy to damage the screen when removing if you haven’t done it before. Good luck!

Your battery could need replacing. How long has it been off the charger? I’d try wireless charging before you try a hairdryer. Worse case scenario, you can buy a battery replacement kit here: iPhone X BatteryComes with everything you could need to fix it the right way.