You could try to enter recovery mode by pressing the power button and the volume up button until it boots into recovery mode. If the screen is still blank chances are that it is a hardware issue. If you want to attempt the repair yourself you should first check if the connector is properly connected before buying any spare parts.
If you can enter fastboot mode (volume down + power button) you can use the xiaomiflash tool. For that you have to download the stock rom from https://androidmtk.com/download-xiaomi-stock-rom-for-all-models and flash it using the xiaomiflash tool