Hey Pauly,
One thing that happens when the firmware updates is that all the settings get reset to factory defaults so the focus mode or focus area may have changed, so ti would be a good idea to check those, especially making sure your autofocus is not set to tracking unless your subject is moving.
I would also recommend doing a focus test in different lighting conditions to cancel out the possibility of lack of contrast or light being the culprit. A lot of these newer cameras can shoot at such high ISO ratings that sometimes people find that even though the image looks bright the AF sensor still lacks sufficient light to focus properly. Basically you want to start by photographing a centered subject with a good contrast of tones, something like a bottle of soda would work well since the logos are usually bright and contrasty, and in good light, something to simulate direct noonday sun if possible. If the camera is able to focus in that situation then you will want to slowly start subtracting light and continuing to repeat the test until you notice it start to have focus trouble.
The reason you want to start in bright daylight with plenty of contrast is that this is the equivalent of a very soft underhand pitch to the camera, it should be able to nail focus quickly and without fail. If you find that the camera struggles in even the most basic situations, something else may be up which would merit a deeper investigation. Let us know how it goes!
