Hi there, kindly check if you can perform the below functions:
Rebooting to bootloader
Step 1. Switch off the device by pressing the Power button for a couple of seconds
Step 2. After that hold down Volume Down + Power keys together for a few seconds
Step 3. Release power key and keep pressing volume down button, you will be then be taken to Recovery mode
Step 6. In recovery Mode go to Reboot to Bootloader by scrolling down/top with volume button
Step 5. When Reboot to Bootloader is selected then press power key to confirm option
Option 2: Performing hard reset(data backup is necessary)
1. Switch off the device
2. When the device is off, press (also hold) volume down key and then press (also hold) power key.
After the device vibrates, release the power key (keep holding volume down key) to enter recovery mode.
3. Select "wipe data/factory reset" by volume down key (or volume up key), and then press the power key.
4. Select "Yes -- delete all user data" by volume down key (or volume up key), and then press the power key to start reset.
5. After the reset is completed, select the "reboot system now" and press the power key to reboot your device.