The Boot ROM (BROM) is a read-only piece of code embedded inside MediaTek microprocessors. It executes at the earliest stage of the device's boot cycle. BROM mode allows a computer to talk directly with the chipset hardware via a USB connection, making it vital for unbricking dead phones, flashing low-level firmware, bypass operations, and forensic data recovery. The Role of eFuses
Redmi 9C (MediaTek Helio G35) User action: Tried to flash a patched boot image via SP Flash Tool after a 2021 OTA update. Result: BROM: Disabled by eFuse 0x146 Outcome: Phone dead. No free fix. Motherboard replacement cost: $40. JTAG repair cost: $80.
The software routes the connection through an automated cloud server running a proprietary server authorization program.
In the context of BROM disablement, manufacturers program specific eFuse bits at the factory to change the boot flow permanently. This action is irreversible; no software operation, whether through an OTA update, factory reset, reflashing, or full UFS/eMMC formatting, can reverse it because the eFuse is located within the CPU and not on the flash memory chip. brom disabled by efuse 0x146 best
If you are reading this, you have likely been staring at a flashing tool log (SP Flash Tool, Miracle Box, or CM2 MT2) that suddenly halted progress with the dreaded error:
: This process requires paid server credits through third-party logistics tools or official service center access logins. Feature Comparison of Fixing Methods Technical Difficulty Risk Factor Success Rate Preloader Custom Mapping Premium Software Required High (Depends on model) Hardware ISP / JTAG High (Requires Soldering) High (Hardware Box) Authorized Server Auth Cost per use (Credits) Medium (Server availability) Pro-Tips to Prevent Device Damage
Known for managing modern security policies by using authentic loader files that communicate via Preloader or Fastboot/EDL states rather than relying on an open BROM. The Boot ROM (BROM) is a read-only piece
Shorting the Test Point forces the processor into BROM mode, bypassing the efuse check that happens during a standard button-combination boot.
Always make a full backup of the preloader and bootloader partitions before experimenting with low-level flashes. Once the efuse is checked and blocks you, there’s no software button to undo it.
While holding the short, plug in the USB cable connected to your PC. The Role of eFuses Redmi 9C (MediaTek Helio
or similar, at which point you can release the short and use your flashing tool. What is the exact model
Select your exact model and choose the function needed (e.g., Factory Reset or Bootloader Unlock).
For technicians: Only an authorized EMI authentication file or direct eMMC programming (JTAG/ISP) can bypass this — and that requires factory-level credentials or hardware intervention.