iPhone won't charge past 1%

The first thing to try is a new battery. I would recommend you buy it from iFixit if you can or a reputable vendor as there are many poor quality batteries on the market. Also, if you have access to a known-good battery, that would be even better.

Is your phone recognized by iTunes? If not, you may have a defective charge port or a failure of the charging circuit on the logic board. Considering that you had water damage, It could be anyone of those possibilities. If you did not remove the shields from the logic board, then you only cleaned ~20% of the board.

Let us know more about the extent of the water damage and what steps you took to clean it up.