SEN0610 mmWave Sensor outputting only "00" via UART on Raspberry Pi 4

Hello, I am currently working on a university capstone project and experiencing a critical issue with the SEN0610 (mmWave Radar) sensor connected to my Raspberry Pi 4. The sensor is receiving power, but it only outputs continuous 00 data through the serial port, regardless of any movement in front of it.

Here are the details of my setup and the troubleshooting steps I have already taken:

[Environment]

Board: Raspberry Pi 4

Sensor: DFRobot SEN0610 (mmWave Radar)

Interface: UART (/dev/ttyAMA0, Physical Pin 8 for TX, Pin 10 for RX)

Language: Python 3 (using pyserial)

[Symptoms]

The sensor receives power properly (the LED turns on, and it generates slight heat).

When reading the serial port, it prints an endless stream of 00 (e.g., 00 00 00 00...).

The data does not change at all even when I wave my hands or move aggressively right in front of the sensor.

[Troubleshooting Steps Already Taken (None solved the issue)]

UART Loopback Test (Passed): I disconnected the sensor and connected the Pi's TX and RX pins directly. The loopback test was perfectly successful, meaning the Raspberry Pi's UART hardware and /dev/ttyAMA0 port are 100% functional.

Power Supply Check: Ensured the sensor's VCC is connected to the 5V pin (tried both Physical Pin 2 and 4), not 3.3V.

Removed Breadboard (Direct Connection): To rule out poor contact issues, I removed the breadboard entirely and connected the sensor directly to the Pi using Female-to-Female jumper wires with tightly twisted connections.

Swapped TX/RX Pins: I tried reversing the TX/RX wires. Doing so resulted in completely no data at all (silence). Reverting to the original setup (Sensor D/T -> Pi RX, Sensor C/R -> Pi TX) brought back the 00 stream, implying the original direction is correct.

Baud Rate Adjustments: Tested both 115200 (Default) and 9600. The issue persists.

Common Ground (GND): Added extra ground connections between the sensor and multiple GND pins on the Pi to prevent floating voltage/reference point issues.

OS & Software Configurations:

Disabled the serial login shell (sudo systemctl disable [email protected]).

Removed console=serial0,115200 from /boot/firmware/cmdline.txt.

Flushed serial input/output buffers before reading in the Python script.

Forced internal Pull-Up resistor on the Pi's RX pin (pinctrl set 15 pu) to stabilize the signal.

Attempted to manually send the "Start Observation" command frame (0x53, 0x59, 0x01, 0x02, 0x00, 0x01, 0x0F) to wake up the sensor.

[My Question] Since the Raspberry Pi's UART is working perfectly but the sensor only outputs 00 despite direct wiring and stable 5V power, could this be a symptom of a defective sensor (Hardware failure of the communication chip)? Or is it absolutely necessary to use a Logic Level Shifter (5V to 3.3V) for the RX pin to prevent this 00 noise issue?

Any advice or insights would be greatly appreciated. Thank you!