When I press the shutter button half-way the autofocus makes the proper noise and the lens moves a little bit like it should, but the image is not properly focussed.

You don't really say if the camera will release the shutter and whether the resulting image is properly focused or not. This could shed light over whether your camera is not focusing properly, or whether you've just got a problem with the image in the viewfinder being blurry.

I have tried with a couple of lenses, and also the same lenses on another camera, so am pretty sure it is not a problem with the lens.

You don't actually say that the same lenses work as they should on another camera body, or that the second lens (presumably not in the bag when it was dropped) but if that is the case then the issue is with the camera body, rather than the lens.

You need to determine if the camera is failing to confirm autofocus or if the problems you see are only due to an issue with the viewfinder. If the camera confirms AF and allows you to release the shutter, does the resulting image appear to be in focus? If so, then your issue is with the viewfinder. It could be as simple as the diopter adjustment wheel needing to be adjusted, or it could be due to the lenses that project the image from the viewfinder to your eye being knocked out of their proper position.

If you take a photo using AF and the resulting images is actually out of focus, then the issue goes beyond just the viewfinder.

If the manual focusing difficulty is also due to damage caused by the drop, the most likely explanation is that the camera's flange ring, to which the lens is attached, and the camera's sensor have been misaligned with reference to each other.

Depending on the focal length and aperture of the lens, misalignment of as little as 50 microns can show up in an image with a wide angle lens and a larger aperture. It would take considerably more than that to prevent being able to manually focus to the point the entire frame would appear to be in focus. But even then a narrow line running perpendicular to the direction of the tilt should be in focus.

If only the sensor moved, that would not explain the failure to autofocus, unless the PDAF sensor buried in the floor of the light box was also misaligned by the drop.

That leaves the flange ring being knocked crooked as the most likely cause of your issue. A very minor misalignment can be corrected with the right (very sophisticated and very expensive) equipment to measure the alignment between the sensor and the flange ring, but if the camera can't AF or you can't even manually focus using Live View, it's way past that point.