iPhone is not starting up.

Hi, my iPhone 4S won't start up.

The Apple logo keeps appearing and disappearing when I plug it into the charger.

I had dropped my iPhone in the water, but that was 3 months ago. After drying it for a night, it was working again.

But yesterday, before I went to sleep I was still able to use my iPhone. I plugged it into the charger and then went to sleep, when I woke up I found my iPhone not being able to start up.

I assumed there was a problem with the battery, so I went to a smartphone repair store to replace it. They said that they put in a new battery, but my phone was still not able to start up, because of the water damage (mentioned earlier).

Also, I can't restore the device since it won't appear on iTunes.

Is there a way of repairing my iPhone or do I need to purchase a new one?

Thanks.