The BMD-300 Series is based on the Nordic nRF52832, which has an operating voltage range of +1.7VDC to +3.6VDC on VCC. Operation outside of this range is not recommended.
The BMD-300 Series has an absolute maximum range on VCC of -0.3VDC to +3.9VDC. Exposure to voltages outside of this range will damage the module. Also note that the absolute maximum range on the I/O pins is different from VCC since the operating level of these pins is based on VCC. The absolute maximum range for I/O pins is -0.3VDC to VCC+0.3VDC. (If VCC is off and at 0V, then voltages on the I/O pins outside of ±0.3VDC will damage the module)
There are a number of conditions to consider, such as Bluetooth receiver input level, NFC field strength, etc. Full documentation for these maximum ratings can be found at the Nordic Infocenter website.