Vivo Y15S/Y15C: EMMC Change, Dead Boot, and Fixing the “No MediaTek Port” Issue
The Vivo Y15s (V2120 / V2147) is a widely distributed budget smartphone powered by the MediaTek Helio P35 (MT6765) processor. Because of its aggressive memory cycle management and budget build, technicians frequently encounter these devices suffering from eMMC wear-out, dead boots, and stuck-on-logo loops.
When a phone reaches a state where it won’t turn on and refuses to show a standard MediaTek USB port on a computer, standard flashing is impossible. This comprehensive guide outlines how to use a Vivo Y15s EMMC Dump File to perform a physical eMMC replacement, reconstruct the partition table, and revive a completely dead device.
Vivo Y15S Device Specification:-
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- Display: 6.51-inch HD+ IPS LCD with a 60Hz refresh rate.
- Processor: MediaTek Helio P35 (MT6765) 12nm Octa-core CPU.
- Ram (Memory) & Storage: 3GB RAM paired with 32GB internal storage (expandable up to 1TB Via External MMC Card).
- Rear Camera: 13MP main sensor with a 2MP macro lens.
- Front Camera: 8MP selfie sensor featuring an f/2.0 aperture.
- Battery And Charger: 5000mAh capacity supporting with 10W standard charger.
- Software Version: Vivo Funtouch OS 11.1 based on Android Version 11 (Go Edition).
- Connectivity: Dual 4G VoLTE, Wi-Fi 2.4GHz/5GHz, and Bluetooth 5.0.
- Security Locks: Side-mounted fingerprint scanner and AI face unlock.
- Build With: Plastic back and frame weighing approximately about 179 grams.
Why the MediaTek Port Disappears:-
Under normal circumstances, when a MediaTek phone soft-bricks, the integrated bootROM (BROM) triggers automatically when connected to a PC. It exposes a MediaTek USB Port (COM Port), allowing platforms like UnlockTool or SP Flash Tool to communicate with it.
If your Vivo Y15s shows no MediaTek port at all (even after holding Volume keys, using a boot cable, or forcing a test point), it points to three structural issues:
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- Total Preloader Corruption: The lowest tier of software instructions inside the storage chip has become completely unreadable.
- Dead or Deadlocked eMMC: The internal flash memory storage controller has crashed, preventing the device’s CPU from executing its initial power-on sequence.
- Hardware Lockup: The device is stuck trying to read a physically damaged storage rail, causing the power IC to drop connection before the computer can register the device.
To resolve this state without a software port, you must bypass the standard USB interface entirely and target the storage chip directly at the hardware layer:-
An eMMC Dump File is a raw, block-by-block layout copy extracted from a fully operational Vivo Y15s motherboard. This backup is typically pulled using a hardware Programmer box like the EasyJtag Plus, UFI Box, or F64 Ultra.
A complete Working Phone’s dump package is divided into three critical areas:
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- ROM 1 (User Data Partition): Usually truncated to a smaller size (e.g., 1GB, 4GB, or 8GB) for repair purposes. It holds the core system hierarchy, framework, and operational OS partitions.
- ROM 2 And ROM 3 (Boot 1 And Boot 2): Tiny, but highly critical areas containing the exact primary bootloaders and Preloader files specific to the MT6765 chipset architecture. Without ROM 2/3, the CPU will never initialise.
- EXT_CSD (Extended Card Specific Data): A configuration file that tells the phone’s CPU exactly how to communicate with the storage chip (bus width, boot partitions, and chip layout timing).
Some Compatible EMMC:-
KM4X6001KM-B321
KMDX60018M-B425
Step-by-Step EMMC Replacement & Repair Procedure:-
If the storage chip is completely dead or unreadable “Health Report: Bad” or “Urgent” errors during hardware diagnostics, you must replace the chip. Follow this systematic workflow using a digital programmer box (e.g., UFI Box or EasyJtag Plus).
Password:- DroidGsm.comVivoY15S
Before soldering a replacement eMMC chip onto the Vivo Y15s motherboard, you must configure its inner logic parameters to match Vivo’s hardware architecture.
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- Place the new or compatible donor eMMC chip into your programmer’s socket.
- Open your tool software and navigate to the eMMC General tab to confirm the chip is properly identified.
- Write the EXT_CSD file from the Vivo Y15s dump directory. This automatically aligns the MTK boot configuration switches.
- Write ROM 2 and ROM 3 into their respective boot partition allocations.
- Write ROM 1 (User Area). If you are using a minimized repair dump, writing the first 1GB to 4GB is sufficient to re-establish the core system partition table.
Preserving or Reconstructing Network Telemetry (NVRAM)
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- If the old eMMC is partially readable via ISP/Socket: Immediately back up the security partitions (
NVRAM,NVDATA,PROTECT1,PROTECT2). These contain your original IMEI and network calibration data. Write these files to your new eMMC chip. - If the old eMMC is completely dead: You must write a global network backup file (Sec File / NV Data) from the dump package. Note that you will need to reconstruct or repair the original IMEI configuration later to comply with regional network regulations.
- If the old eMMC is partially readable via ISP/Socket: Immediately back up the security partitions (
Reviving the MediaTek Port and Final Flashing:-
Once the pre-programmed eMMC is physically attached to the board, your initial diagnostic block is broken. Because the CPU can now read a valid preloader sequence from the new chip, the device will instantly re-enable its MediaTek USB COM Port when plugged into a PC.
To bring the device out of its bare-bones testing state and resolve any leftover “Hang on Logo” issues, follow these final steps:
- Connect the phone to your computer via USB (no test-points or hardware keys should be required now).
- Open your preferred service tool, such as UnlockTool, SP Flash Tool, or Miracle Power Tool.
- Select the official Vivo Y15s Scatter Firmware package.
- Flash the complete, official firmware to fill out the remaining system, vendor, and user data fields.
- Wipe data/factory reset via recovery mode once the flashing pipeline finishes, then power on the device.
