Comprehensive Guide: Resetting Samsung Feature Phones Using Master Codes
Samsung keypad devices—most notably the Samsung Guru series (Guru Music 2, Guru 1200, Metro, etc.)—are legendary for their durable hardware, straightforward proprietary operating systems, and massive battery life. However, like any embedded electronic system, long-term operation can lead to software glitches, memory heap saturation, forgotten lock passwords, sluggish menus, or continuous restarting loops ("boot loops").
For service technicians, mobile repair professionals, and end-users, master diagnostic strings (MMI and USSD codes) provide a fast, software-free method to restore internal registers to original factory defaults.
Samsung keypad devices—most notably the Samsung Guru series (Guru Music 2, Guru 1200, Metro, etc.)—are legendary for their durable hardware, straightforward proprietary operating systems, and massive battery life. However, like any embedded electronic system, long-term operation can lead to software glitches, memory heap saturation, forgotten lock passwords, sluggish menus, or continuous restarting loops ("boot loops").
For service technicians, mobile repair professionals, and end-users, master diagnostic strings (MMI and USSD codes) provide a fast, software-free method to restore internal registers to original factory defaults.
What Does the *2767*3855# Code Do?
In Samsung’s proprietary keypad firmware architecture, *2767*3855# is designated as the Full Factory Reset (EEPROM Master Wipe) command.
Partition Reconstruction: The phone reinitializes the file allocation table within the embedded NOR/NAND flash memory.
Master Lock Bypass: If the phone has a user-defined Phone Lock password, Privacy Protection lock, or Keypad Lock code preventing access to system menus, executing this string directly clears the security flags and resets passwords back to default (0000 or 00000000).
Cache & Transient Register Purge: Temporary network registration tables, accumulated SMS indexes, and damaged heap memory caches are completely discarded.
Autonomous Execution: Unlike menu-based resets, entering this exact dial string triggers an automatic hard restart sequence without asking "Are you sure?".
In Samsung’s proprietary keypad firmware architecture, *2767*3855# is designated as the Full Factory Reset (EEPROM Master Wipe) command.
Partition Reconstruction: The phone reinitializes the file allocation table within the embedded NOR/NAND flash memory.
Master Lock Bypass: If the phone has a user-defined Phone Lock password, Privacy Protection lock, or Keypad Lock code preventing access to system menus, executing this string directly clears the security flags and resets passwords back to default (
0000or00000000).Cache & Transient Register Purge: Temporary network registration tables, accumulated SMS indexes, and damaged heap memory caches are completely discarded.
Autonomous Execution: Unlike menu-based resets, entering this exact dial string triggers an automatic hard restart sequence without asking "Are you sure?".
Pre-Reset Requirements & Verification Checklist
Before dialing low-level service strings, ensure the device environment meets these operational standards:
Remove the SIM Card: Eject both SIM 1 and SIM 2. Some cellular network operators block specific dialed strings, or the SIM application toolkit (STK) may intercept dialed USSD patterns.
Remove the MicroSD Card: To avoid inadvertent file index corruption during sudden power drops, take out any external memory cards.
Check Battery Voltage: The battery must hold at least 50% charge (or show at least 2 full bars). If the battery dies mid-reflash during the EEPROM erase cycle, the boot sector may become corrupted, requiring a hardware box reflash (e.g., Z3X or Miracle Box).
Stable Battery Connection: Ensure battery terminal pins are clean and tight so the battery does not shift loose during the reboot phase.
Before dialing low-level service strings, ensure the device environment meets these operational standards:
Remove the SIM Card: Eject both SIM 1 and SIM 2. Some cellular network operators block specific dialed strings, or the SIM application toolkit (STK) may intercept dialed USSD patterns.
Remove the MicroSD Card: To avoid inadvertent file index corruption during sudden power drops, take out any external memory cards.
Check Battery Voltage: The battery must hold at least 50% charge (or show at least 2 full bars). If the battery dies mid-reflash during the EEPROM erase cycle, the boot sector may become corrupted, requiring a hardware box reflash (e.g., Z3X or Miracle Box).
Stable Battery Connection: Ensure battery terminal pins are clean and tight so the battery does not shift loose during the reboot phase.
Step-by-Step Reset Procedure
Follow these sequential steps to perform the wipe and cycle the boot phase properly:
Power on the Device
Insert a charged battery and press the Red (End Call/Power) key until the Samsung splash screen appears. Allow the phone to reach the main home screen or emergency dialer screen.
Verification: The main wallpaper, clock, or "Insert SIM" notification is visible.
Access the Dial Pad
If prompted with an Emergency Call screen due to a lock, open the keypad dialer. If already on the home screen, type directly onto the keypad.
Verification: Number inputs appear clearly on the screen.
Enter the Master Reset Code
Carefully dial:
Plaintext*2767*3855#
As soon as the final # is typed, the device will immediately change screens. Do not press the Green (Call) button.
Verification: The display will show a system message such as "E2P Full Reset", "Please Wait", or an animation indicator.
Observe the 1-Minute Reboot Cycle
Leave the device completely untouched on a flat surface for 60 seconds (1 full minute).
The screen will go blank or turn solid black/white.
The internal processor erases the data block and rewrites factory registers.
The phone will power off entirely and initiate a cold boot automatically.
Verification: The phone plays its startup chime, flashes the Samsung model logo, and enters the initial Language & Date setup wizard.
Follow these sequential steps to perform the wipe and cycle the boot phase properly:
Power on the Device Insert a charged battery and press the Red (End Call/Power) key until the Samsung splash screen appears. Allow the phone to reach the main home screen or emergency dialer screen.
Verification: The main wallpaper, clock, or "Insert SIM" notification is visible.
Access the Dial Pad If prompted with an Emergency Call screen due to a lock, open the keypad dialer. If already on the home screen, type directly onto the keypad.
Verification: Number inputs appear clearly on the screen.
Enter the Master Reset Code Carefully dial:
Plaintext*2767*3855#As soon as the final
#is typed, the device will immediately change screens. Do not press the Green (Call) button.Verification: The display will show a system message such as "E2P Full Reset", "Please Wait", or an animation indicator.
Observe the 1-Minute Reboot Cycle Leave the device completely untouched on a flat surface for 60 seconds (1 full minute).
The screen will go blank or turn solid black/white.
The internal processor erases the data block and rewrites factory registers.
The phone will power off entirely and initiate a cold boot automatically.
Verification: The phone plays its startup chime, flashes the Samsung model logo, and enters the initial Language & Date setup wizard.
Diagnostic Reference Table: Common Samsung Master Codes
Troubleshooting Common Post-Reset Scenarios
Scenario A: Phone Displays "Emergency Only" or Blocks the Dial String
Cause: The current security lock profile on the phone prevents entering standard USSD codes.
Resolution: Power down the unit. Remove the SIM card entirely. Power on without a SIM. If prompted with an "SOS" or "Emergency" soft-key, select it to expose the dial field, then input *2767*3855#.
Cause: The current security lock profile on the phone prevents entering standard USSD codes.
Resolution: Power down the unit. Remove the SIM card entirely. Power on without a SIM. If prompted with an "SOS" or "Emergency" soft-key, select it to expose the dial field, then input
*2767*3855#.
Scenario B: The Phone Stays Completely Blank After 1 Minute
Cause: Insufficient battery voltage dropped the processor into a low-power shutdown mid-execution.
Resolution: Pull the battery out for 10 seconds. Reinsert the battery, connect the micro-USB/charging pin, ensure the charging animation appears, charge for 20 minutes, and power on manually.
Cause: Insufficient battery voltage dropped the processor into a low-power shutdown mid-execution.
Resolution: Pull the battery out for 10 seconds. Reinsert the battery, connect the micro-USB/charging pin, ensure the charging animation appears, charge for 20 minutes, and power on manually.
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