The external battery connector on the Grove XBee Interface board is not fully functional. The FTDI chip is not powered via the external battery connector, and thus acts as a ground, so any XBee pin connected to the FTDI chip will be pulled low. The most visible result of this is the module booting into SPI mode due to DOUT (pin 2) being pulled low during startup, but this may also result in unexpected behavior on other pins.
If using the Grove XBee interface board, it is recommended that the board be powered via the micro-USB port at 5V. For details on how to power and wire connections to the XBee module, see the User Guide for that product: https://www.digi.com/support/supporttype?type=documentation
Nov 22, 2019