Unplug the phone, force a restart, clear active processes, re-enter EDL mode, and double-check your file match. Device Not Found (COM0) Defective USB drivers or bad physical connection.
This comprehensive technical guide explains what the Firehose programmer is, why it is critical for repairing Qualcomm-powered smartphones, and how to safely utilize it to unbrick your device or clear locks. What is an OPPO A57 Firehose File? oppo a57 firehose file