To fix your soda spilled on your MacBook and make its screen go black and won't turn it back on, you need to check whether your mainboard is intact. If your mainboard has been corrupted, there is no way to turn your MacBook on, and the only way to fix it is to send your MacBook to a professional office for repair.
What you need to do now is to take out all the removable parts, especially your battery, and then dry them with a soft cloth. Wait for a few days, then move them back and try to turn your MacBook on again. If still not working, send your MacBook for repair immediately.
