Hi,
There is an issue with the internal clock suggested by the BOM for the CC256x module: the OV-7604-C7 micro-crystal. The OV-7604-C7 pin values are a miss-match to the footprint on the CC256x PCB. This may sound confusing, but I will describe this as best as possible.
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The footprint pads in the CC256x are good. The slow clock pad goes to the correct slow-clock trace into the CC256x chip. The GND pad goes to ground. The VCC pad and EN pad traces go to 1.8V_VCC. This looks good.
The OV-7604-C7 footprint is a match to the footprint pads in the CC256x module. This is good too.
Now, let's take a loot at the 
for the micro-cyrstal. Pay a good attention to the designator name for each pin #.
If we solder the crystal chip with the clock pin to the clock pad of the CC256x, the GND, VDD, and EN pin will be positioned on the wrong directions in respect to the pad of the CC256x.
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Here is a way to get around this,
Remove R26 (it is a 0 ohm resistor)
Remove R34 (this is a 10.0k ohm resistor that we will need to sacrifice)
Solder the crystal as shown, and short (red wires) the EN and CLK pads to route them to their correct traces.
As you can see above, VDD and EN are now going to 1.8V. The clock signal is going into the CC256x clock pin. The GND is grounded. In this arrangement, the OV-7604-C7 micro-crystal will supply the required slow-clock for the CC256x module internally.
