Usually features a small logo or the word "Fastboot". It is used for communicating with a computer and flashing low-level system partitions.
If your physical buttons are not working correctly, you can use a computer to trigger the mode: Enable Debugging Settings > About Phone how to open fastboot mode on oppo a37 better
Enable by going to Settings > About Phone and tapping the Build Number seven times. In Developer Options , enable USB Debugging . Usually features a small logo or the word "Fastboot"