If you cannot use the physical buttons, you can use the Android Debug Bridge (ADB) tool:
If your device is fully operational and you prefer using a desktop workstation, you can execute an command-line function using the Android Developer Toolkit. Prerequisites: A desktop computer running Windows, macOS, or Linux. An authentic USB data cable. Installed Google SDK Platform Tools on your PC. Step-by-Step Instructions: How to Open Fastboot Mode on OPPO A54