I doubt very much that these are symbols of any type. The look more like where wooden beams have been set into the walls at one time.

The inscription is not a message. It's a "spell". The symbols are neither scripts nor glyphs. They are "sigils" (check Wikipedia for understanding and a picture of some known Hebrew sigils). Cainan of the bible (Adam's grandson) lived 910 years (as did most people before the flood changed our living conditions) and is reported in Arab folklore as having miraculous powers and a universal empire at the time when the Mayan calendar was created (3114 BC). I suspect Cainan practiced this form of Hebrew magic and also gave the Mayans their calendar. The exact nature of the spell would be known only to the creator of those particular sigals and those to whom he revealed it.
Love your website. Hope I have time to look at more ..Patrick (a well-informed, born again, tongue-speaking Catholic and former occultist)