I have 5 identical HM-10 Bluetooth modules.
One of them works great. I plug it into my breadboard and I can talk to it with AT commands.
But the other four modules don't respond to commands. The red LED blinks like it is searching for a bluetooth connection but when I try to send any command I get no response.
The Arduino sketch I'm using is called SerialIn_SerialOut_HM-10_01 which can be found On this site.
I don't think I have an 80% hardware failure rate here; that would be crazy, right? Any other ideas about what I can do to regain control of these?