I had this problem and fixed it. At the bottom of the bean container is a tab that extends about a quarter of the way around. This tab is designed to fit into the base inside a quarter-circle groove that rotates back and forth slightly when the bean container is installed or removed. In my case, the groove on the base was not aligned correctly, so I inserted a blade screwdriver into the groove and rotated it gently in a counter-clockwise direction until it stopped. After this, I could install the bean container as expected.
First of all the solution IS NOT in the manual. Second of all, you shouldn't go taking the grinder apart. It is soooooooo simple. You just have to rotate the black part where the long **** is counter clockwise until it's at about 2 o'clock. The blade slips right off. I saw a post about someone sending it in for repair for this same problem. It must be a lie because this is not a problem that needs a repair solution. It is a very simple fix. No tools no springs popping out at you, no nothing. Again, Just hold onto the black part with the ****. It moves. Turn it counterclockwise to about 2 o'clock. The blade slips off.
Yes! I had the same issue with putting the burr in upside down and then twisting it an effectively "locking" it in there incorrectly. I tried the "knife" solution that worked for some people here, but it was placing the bean container back on and twisting counter clockwise that did the trick!
So glad I found this thread and didn't give up trying to fix my burr grinder (which we love).
I had the same problem with too fine a grind when I took mine completely apart to clean (including the lower burr). The solution I finally came around to was to further tighten the star-shaped screw which holds the lower burr assembly in place. I had originally just tightened it until the lower burr until the lower burr assembly started to turn with the screw, but that wasn't enough. So I held the assembly in place and tightened the screw further and I'm back to my previous grind coarseness/fineness.