Continue holding Volume Up until you see a screen with small text or a green android logo. This is Recovery Mode , not Fastboot.
Now type the reboot command:
You should now see the Fastboot screen (usually a dark screen with small white text listing your device’s serial number and partition info). This is the easiest method for users who already have USB Debugging enabled. How to Open Fastboot Mode on REALME C12
Press and hold the Volume Up button and the Power button simultaneously. Continue holding Volume Up until you see a
Type the following command and press Enter: How to Open Fastboot Mode on REALME C12
adb devices (If your device shows “unauthorized,” check your phone and allow USB debugging access.)