Screen is broken and not starting

@sneha25720 this "not opening, and screen not working and it's not vibrating" does not necessarily mean it's a bad screen. What it seems like is that your Xiaomi Mi Note does not get any power. Start with the basic testing. First you want to check your power supply. Make sure it has the proper voltages. Check to make sure connectors are not bend etc. After that, check the charging port. Clean it of any debris etc, use a few puffs of air to clean it out. Make sure there is no corrosion, debris etc. that prevents it from working. If none of this works, get a ammeter and see if your phone draws any amperage from the charger.

You may also have to consider replacing the battery. A depleted battery can no longer be charged. Measure the voltage on your battery connector with the charger plugged in. You should get around 4.2V If you do not get this voltage If you don't get that voltage check your flex cable coming from the charging board. Make sure it is seated properly and does not have any tears or other damage on it.