The Brookstone manual claims it will fully charge after 3-5 hours, but it takes much longer then that. Mine does not indicate green light, but it seems it stops blinking red when its fully charged. After that it run on power directly from the ac-adapter.
If you keep it connected to the AC-adapter after it have stopped blinking red (do not disconnect it at all), it will start to run on the adapter and will not turn off. You will feel the AC-adapter gets hot while its running, something it does not while regular charging.
If it still dont stop blinking red after having it connected to power for 3 days, your AC-adapter is probably faulty. This happened to me, and after allot of research I found this replacement from a US seller on ebay (only five dollars included shipping).
Good luck with your projector. It a really cool little thing, but it has some design flaws.