How could I get the keys to work after a spill?

I recently spilled 5 big drops of water mixed with tomato juice on the keyboard of my MacBook. I dried it out and cleaned up the keys.

My big mistake was to turn it on again after only 20 minutes and then i realised that components had been damaged since the full column of keys (9, o, l, : and arrow up and down) are not working any more.

I then directly turned it off again and put the keyboard face down on a heat of rice for 48 hours.

After 48 hours, the same column of keys doesn't work anymore and i'm looking for the best solution to fix my problem.

I completely disassembled it (excepting the backlight and keyboard which are stuck to the top case) before trying to turn it on the second time. I cannot see any sign of spill under the backlight.

Do you think that only the keyboard can be damaged?

What should my my next step for you? Should i try to disassemble the keyboard and clean it or there's no chance for my dead keys to work again?

How could I be sure that my keyboard only is damaged without changing it? (I'm writing with an external USB keyboard right now).

Thanks a lot

PS: I have been trying to be very careful when disassembling the MacBook and especially the connectors of the logic board, but some very little chips seem to be very fragile. Is there many precautions to take while doing it? What are these?