It's a very common and stupid bug by Xiomi Mi.
It can be solved easily but u need to have more patience (mooorreee)
Even if you connect the charger, you wont be able to see any sign of charging and continues blink (kind of boot loop). I am sure this should be the problem for you (not only you, more than a millions)
1. Connect the phone with a charger, you may or may not see any sign of charging
2. Wait for at least 15 minutes and max of 45 minutes until you notice some sign of charging
3. Never disconnect the charger even for a single second while doing it
4. After a good amount time you get any of the below,
5. Phone booted without any issue :-)
6. If not use Power + Vol Up button to boot into recovery mode wipe all,
7. I not Vol + Down to fast boot. Keep charging until u see any sign of charging.
8. Try with another charger if it didn't
Let me know whatever result u get, I will give u the good solution, but don't forget to reply