On newer Exynos (S8, Note 8, S9, Note 9), download mode is locked if the bootloader fuse is blown (Knox 0x1). However, "Exynos USB Device4000 Verified" can still be achieved using a USB-C UART jig (like the MHL-to-UART converter). This sends a 0xBC command to the boot ROM, bypassing the Knox check temporarily.
Understanding the difference between verified and unverified states can save you hours of debugging. Here is a comparison:
| State | Device Manager Display | Driver Used | Communication |
|-------|------------------------|-------------|----------------|
| Unverified | "Unknown USB Device (Device Descriptor Request Failed)" or "Exynos USB Device4000" with a yellow exclamation | None or generic WinUSB | Blocked; host cannot send any download command |
| Verified | "Exynos USB Device4000 Verified" | Samsung USB Driver for Mobile Phones (or libusb/KieS) | Full handshake; ready for DOWNLOAD or PIT commands |
| Signed Verified (rare) | "Exynos USB Device4000 (Secure)" | Samsung combined driver | Only accepts Samsung-signed bootloaders | exynos usb device4000 verified
If your device remains in the unverified state, Odin will freeze at "SetupConnection" and Heimdall will report "Failed to claim interface."
Developers often use tools like Heimdall (open-source flashing utility) which communicate with the Exynos download mode. Before Heimdall can flash a custom recovery (e.g., TWRP), it must first detect a verified device. If you see "Exynos USB Device4000 Verified," Heimdall’s detect command will return a positive ID. On newer Exynos (S8, Note 8, S9, Note
The Exynos USB Device 4000 is not a standard MTP or ADB interface. It is the proprietary USB download mode present in modern Exynos SoCs (from Exynos 8895 onward, but standardized around the 9820/2100 era). When your device enters this mode, the boot ROM (iROM) has failed to find a valid signature in the bootloader chain—or has been deliberately forced into download mode via key combinations or USB command.
Key identifiers:
su
echo 0 > /sys/class/android_usb/android0/enable
echo "4000" > /sys/class/android_usb/android0/idProduct
echo "04e8" > /sys/class/android_usb/android0/idVendor # Samsung
echo "usb_device" > /sys/class/android_usb/android0/functions
echo 1 > /sys/class/android_usb/android0/enable
Check:
cat /sys/class/android_usb/android0/functions
Should show usb_device or gadget.