Electronics and water dont mix, what you should have done is as soon as you retrieve the phone from the water, is remove the battery, then bringing it for repair, as opposed to what you have said that you let it dry and then re-installed the battery.
Cellphones, specially Nokia, well all of them, have IC's or circuit compnoents,as all electronics have,
the only difference is Nokia IC's are installed on its board or circuit board by lead balls so called BGA Balls, actually looking like its floating from the board. When the phone is subjected to water, water seeps through and inside these lead balls, rushing in between the IC and the main board, and never leave there, nor the water will dry. One should really dry it out using special solvents and a "HOT AIR" gun.
From the time you re-installed the battery back, you actually induced short circuiting because some, or all IC's have water in between them and the board.
Here is a picture of it for you to understand, notice the "BALLS" of lead, and the empty spaces in between them,
So i guess you have done harm again by subjecting short circuiting on the phone.
I therfore suggest you bring it in at any NOKIA care center for repairs, You wont be able to fix that by yourself, for the phone now may have damages to any IC's thats why it shuts itslef off, and never charges, NOKIA high end phones have a certain defense mechanism to turn itself off when triggered with water damage.(again refer to the picture)As you can see there are many IC that could be any or all of them are now damaged.
Hope this clears your questions, and I highly suggest that you remove the batteries now, and never attempt to power it and/or charge it until it is looked upon by a certified Tech.
Thank you for using Fixya.