Keeps saying fill beans container when already full

The machine understant that there is not any beans in the container by the mesuring how easily the grinder motor rotates. If there is not any beans in the grinder motor rotates freely. In your case means that the beans from container are blocked to enter down to the grinders disk plates or they partialt enter, so the motor runs more freely and machine understant that there ae not enough beens. So you need to remove the beans and container and by the use of a vaccum cleaner remove all remainings from the grinders entrance and funel. You can also use a brush to remove any coffe oils and remianing so the bean can easily slide inside the grinder.

After a tons of browsing and debugging finally I got the real solution to my similar problem with a Saeco Minuto HD8763 coffee machine: the root cause was a bad hall sensor and a weak magnet at the grinder toothwheel (the left magnet whcih was removed from it's original place). The upper one was okay and down under there is the replacement magnet which I made from a piece of HDD neodymium magnet and glued to fix it.
The original hall sensor was marked as "210k 3491" ("HAL506K" based on some other service manuals) and the new one was a cheap non-smd but same size, unipolar "TLE4905" type.