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: If the phone is "dead" (won't turn on or enters a boot loop), the Firehose file enables a full factory firmware re-flash.
The term progemmcfirehose likely originates from a mistranscribed filename like prog_emmc_firehose_660_ddr.elf or a forum user combining “programmer” + “eMMC” + “Firehose”.
: Use a pair of metal tweezers to touch both pads simultaneously while plugging the USB cable into your PC. Verification : If successful, your PC will recognize the device as Qualcomm HS-USB QDLoader 9008 Official Software Updates (2021)