Default [HOW TO] Fixing the 'battery over-heating' sign on your phone.

Here’s the reason for anyone of you who is facing this over-heating problem with your P50* phone: your Kernel is NOT compatible with your ROM. Colors will likely be displayed properly, but the over-heating problem will be persistent, and will shut-down your phone as soon as it’s booted. Don't panic; there’s a very easy solution to this problem; however, it will involve installing another ROM which is compatible with that Kernel (or back to your original ROM). I’d suggest you do some research on the ROM you are using with that Kernel, and to get a compatible one flashed, or just to get the previous ROM installed on it again. Follow the following steps.

1. Plug-in your phone to its charger. The ‘over-heating’ sign will disappear.

2. Open your internet. If you had done a complete factory reset before installing the ROM, just connect to Wi-Fi.

3. Install your previous ROM back to get your phone back to normal and not get that ‘over-heating’ sign again. (Hopefully you know it! If not, PM and tell me.)

4. Now, if you want a different ROM installed, you’d be better off installing one that comes WITH a Kernel. Separate ROMs and Kernels are for experienced users; hence, sticking with those which come with both wouldn’t hurt until you are aware of what you’re doing and know how to handle any problems that may occur.

If you have any questions, please ask. I am extremely busy with exams, but still managed to get this post written.
Note: No CPU frequencies or anything else had caused the problem. It's not very easy to get a phone over-heated.

Good luck!