My phone is fully charged but not turning on it is only showing up it'

Hey hi Sayni, it looks like your stuck on a boot loop, don't worry, it can be fixed.
One simple solution you can do is doing a soft reset, DONT WORRY, IT WONT RESET YOUR DATA OR DO ANY BAD. I am going to differentiate between soft reset and hard reset.

Soft reset means that your restarting your device without loosing any data on your phone except for any data that is within your RAM. Its not a thing to worry about as RAM won't get your photos or video deleted. RAM just has the app modules and stuff like that, which it thinks that the user would open and if you open it, it opens up faster than the hard drive itself. So no need to worry about data in RAM as it is stored nicely in your hard drive. In general, soft reset and restart are basically the same thing.

Hard reset means that erasing all your data and resetting your phone, just the way it was after it exited the factory. Don't do hard reset/factory reset.

Also, to do a soft reset, hold the power button for about 10-15 seconds and then the device would automatically soft reset/restart. It solves minor glitches that stops the device to function normally.

IF YOU STILL ENCOUNTER THE ISSUE, HERE IS A BETTER APPROCH TO THE PROBLEM:
I found out on the internet that entering recovery mode might help you out. Here is how you enter recovery mode:
1) Make sure that your phone is turned off
2) Press and hold the Volume Up and Power buttons simultaneously until the Mi logo appears.
3) Release the buttons when the recovery mode screen appears.

The device should function normal after you exit recovery mode once your done having a view of it. Exiting it is very easy, there are only 4-5 options that you can choose with the help of volume button and the power button only. One of the button would have a option named as reboot (which means boot normally again (restart)), also make sure to check out this video on YouTube, it will help you out. If none of the other options work then your only left with flashing your device, its a technical thing (easy for daily users but technical for newbie's). You can just have a overview to how does flashing a device looks like. THE VIDEO.

I hope this helps you out and gets your phone fixed. If you want more information about how to flash device ask it in another question mentioning me in the comments (like this -> @sabotaged ) Copy the bold text given in the parenthesis and paste it in the comments section in the new question and will tell you how to flash a device, I will flash my own device for that purpose =).... At last, have a Gorgeous day, stay good, stay well, be happy. Thank you for all those who read till here, really appreciate the efforts made by the one who made it to the end (it took 1.2HR to write this one) Anyways, bye =)