I feel your pain. I once dumped some grape Crush into my laptop. Fortunately the colour made it easy to clean up once I opened the case, but some of my keys were still sticky underneath for a long while afterwards.
When you say that the USB and SD slots are still not working, are you saying that the system reports them as unavailable somehow, or just that they aren't responding to your usb sticks and SD cards?
There should only be low-voltage electronics near the plugs, and soda isn't the strongest conductor in the world, so I don't think you've done any damage anywhere but near the plugs. If the problem is just that it doesn't seem to see your devices, I would try getting something small, like a folded-up business card, and using it to rub plain water onto the terminals in the USB slot. Then try plugging in a device which is known to be good. If it is still not recognising the device, try again a few times. (You might want to apply the same procedure to device-side plug after removing it, in case you've transferred the contaminant across.)
Then I'd try the same thing with the SD slot.
2017 FFE Magnetic