The camera documentation says the mini cameras use an AR (anti-reflection glass) window.
It keeps dust off your sensor, but since you have already opened it, you might need to clean your sensor now.
Amazon sells camera sensor cleaners. Get the ones with the small spades. The ones for full frame sensors may not fit into the mini camera tube.
Be really careful not to scratch the sensor. That is why you don't want to use just any cloth that can cause micro scratches -- the scratches that are not visible under a loupe may still be visible in the images.
After cleaning, try to reassemble in a dust free and dry room.
Clean the inside of the AR glass too, before screwing the glass holder back on -- and never remove it again.
You may need to rinse and repeat a few times to completely rid the sensor and inside of the AR window of dust. A UV lamp often helps you locate the small dust particles.
The outside of the AR window can be cleaned any time. Soft lint free lens tissue is sufficient to clean either surface of the the AR window.
You can tell if the dust is located on the sensor or the AR window by looking at how distinct the dust spot and the size. The dust on the sensor tends to be very dark, distinct and small spots. The dust on the window tend to be more translucent in nature and larger. The dust on your filters are even larger and even more translucent -- those are easy to remove by subtracting flat frames. If the dust does not move as you rotate your camera, it is probably on the sensor or the camera window.