Single Channel Relay not happy | Arduino Modbus Project

I have received two single-channel Modbus-enabled relays, but neither seems to power on. According to the specification, they should operate within a voltage range of 7 to 24 volts, but this isn't happening (no LED turns on, no nothing). I even put together a second Arduino to iterate through all possible slave numbers (1 to 255) to determine if the relays were functioning without an LED indicator. Unfortunately, this effort was unsuccessful.

After testing both relays without success, I decided to order two more: one single-channel and one two-channel version. In the meantime, if you have any recommendations for reliable, Modbus-enabled relays that you have tested and can vouch for, I would greatly appreciate it.