I have ordered over 60 Redbear Duo’s and it seems like they always fail or get in some sort of stuck state. Ive had these problems with the Particle photon too.
After sometime of running code a few days will pass and it seems like out of nowhere it will stop working. When the redbear starts up it first starts with blinking white, as it should, then it goes straight into blinking blue, when it should go into blinking green to atempt to connect to a wifi network that was already setup on it. When this happens it will be stuck in blinking blue. It looks very much like the same blinking code as if it was in setup mode, however, it is not in setup mode, it does not briadcast BLE and no information on serial line either.
Even if i try to go into safe mode it goes straight back into blinking blue. I also cant put it in setup mode. This has happend many times out of nowhere,becuase it would always run the code fine at first.
My code is very long, the only thing i use system wise is SYSTEM_THREAD(ENABLED) and i also use the wire library.
It would be nice to have a consistent working product, ive had many problems with photons in the past as well.
UPDATE: The photons do broadcasts a wifi network in this mode, as if its a photon in setup mode.