This is the most common way to access Fastboot Mode directly from your device: : Completely turn off your : Press and hold the buttons simultaneously for a few seconds. : Once the Fastboot Mode text or screen appears, release all buttons. Method 2: Using ADB (Requires a PC)
If you want, I can provide ADB/Fastboot download links and driver installation steps for Windows, macOS, or Linux. Which OS do you use? how to open fastboot mode on oppo a37 better