Help with getting iPhone 4s to charge

Hello

I'm wondering if someone might be able to advise me on how to get my husband's iPhone 4s to work again, please?

The history of events is this:

-- iPhone 4s was working fine

-- iPhone 4s was dropped down the loo (oops!)

-- iPhone 4s was working ok for several months, apart from issues with the speaker not working too well

-- iPhone 4s was then left in the cupboard for nearly a year (husband bought a new phone)

I recently took the iPhone 4s out of the cupboard and placed it on charge. It looked like it was charging (it showed the battery picture) but, when I checked a couple of hours later, all I had was a black screen.

The steps I've taken to get it to work (none of which have worked):

-- I tried pressing the home and start buttons together for 30 seconds. Result? no change (black screen)

-- I tried reconnecting the iPhone 4s to iTunes. Result? no change (black screen)

-- I replaced the battery (bought one from this site). Result? no change (black screen)

-- I charged the battery for over 30 minutes and tried these steps again. Result? no change (black screen)

-- I tested the phone charger on another phone and the phone charger works perfectly, so it must be a problem with the phone.

Any ideas?

Many thanks, Emily