AFAIK, if the Beats Flex status LED is flashing white, that would indicate that they are either ready to pair or reconnect.
Just to make sure you didn't miss anything when you tried to reset them, here is the procedure to do so:
- Press and hold the volume button on the left control module and the power button on the right control module for 15 seconds (until the light flashes), then release the buttons.
If they don't reset, then your next step is to contact Apple Support directly for further assistance with this matter.