Brom Disabled: By Efuse 0x146 Best
Device: 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.
Look for markings on the main chip (e.g., RK3566, RK3588, Allwinner, Amlogic). Different vendors use different error codes.
To understand the error, you must first understand BROM.
BROM (Boot ROM) is a tiny, read-only memory chip embedded inside the main processor (SoC—System on Chip) of your MediaTek-powered device. It holds the very first code that runs when you power on your phone. Think of it as the BIOS of a computer, but more primitive and immutable.
BROM’s job is simple:
This "download mode" is what tools like SP Flash Tool, Miracle Box, and CM2MT2 exploit to flash firmware, repair IMEI, or remove FRP. For years, this backdoor was wide open.
Free tools often fail against 0x146. Commercial boxes are updated constantly to defeat new eFuse mechanisms.
Best Box for 0x146: Miracle Box (Thunder Edition)
Infinity CM2MT2 also has a specific option: "BROM E-fuse 0x146 handler" in the settings. Check that box, then try the "Force BROM" mode. brom disabled by efuse 0x146 best
Before dissecting the error, we must understand the Boot ROM (BROM).
The BROM is a small, read-only memory embedded inside the MediaTek CPU. It is the first code that runs when your device powers on. Its job is simple:
For years, repair technicians exploited the BROM mode because it typically allowed low-level reads/writes to flash memory, even if the device was bricked or locked. This changed drastically with MediaTek’s introduction of Secure BROM and efuses.
If the eFuse is truly blown (indicated by the specific register readout), here is the reality: Device: Redmi 9C (MediaTek Helio G35) User action:
For a few years, certain chipsets had a vulnerability in the BROM that allowed bypassing the 0x146 check (e.g., the infamous "BM EMMC" or "BROM blink" exploits). MediaTek has patched many of these, but old or budget chipsets remain vulnerable.
In simple terms: Your phone is bricked, and you are locked out of the factory recovery mode.
The technical reality: When a phone receives an official OTA (Over-The-Air) update or a specific security patch (usually Android 9, 10, 11, or 12 with MediaTek), the manufacturer "blows" the eFuse at address 0x146. This permanently tells the BROM: "Do not accept unsigned or unauthorized flash operations."
Result: Tools like SP Flash Tool can still detect the phone, but the second they try to send a "DA" (Download Agent), the BROM rejects it and throws error 0x146. This "download mode" is what tools like SP
