Seeed 24GHz mmWave Sensor no output

I bought one XIAO ESP32C3, one 24GHz mmWave Sensor MR24HPB1, one 24GHz mmWave Sensor MR24HPC1, then try on Arduino, but no sensor data output in Arduino serial monitor.

#1: XIAO ESP32C3 + MR24HPB1: following demo1 on GitHub - limengdu/Seeed-Studio-MR24FDB1-Sensor: Seeed_24GHz_mmWave_Radar_Sensor. In Arduino serial window, radar.newData is always 0.

#2: XIAO ESP32C3 + MR24HPC1: following demo1 on GitHub - limengdu/Seeed_24GHz_Human_Static_Presence_Module_Lite. Same as #1, radar.showData() has no output.

Both cases have same connection as below:
mmWave sersor ESP32C3
5V ------ 5V
GND ------ GND
RX ------ D6
TX ------ D7

Please help.