Yes, you can write code that renders your Photon inable to reach the cloud.
Unless you are using dedicated SYSTEM_MODEs or the new beta multithreading feature SYSTEM_THREAD(ENABLED) any code that prevents your program from leaving loop() while not calling delay() or Particle.process() will most likely break the cloud connection.
But if you've got a very fresh Photon and flashed it the first time, it might rather be that the auto firmware update might have come in your way
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