Michael

I have a water damaged iPhone 4S that works when I put a battery with charge in. However, when plugging into a power...

Main-board issue. Send to Nokia Care for repair.

Sounds like either you charger or DC jack is faulty. Ensure all leads are properly connected. Test your charger using a multimeter for the voltage given on the sticker on the charger. If you are getting the correct voltage, it maybe the DC jack which is a common fault on laptops. You can test the DC jack by opening the laptop up and testing for voltage where the jack meets the board. If the DC jack and charger are working, the power board is probably at fault.

Weigh up the pro's and cons, if their are more pro's do it, and if things go wrong, at least you can be happy that you made a logical decision. If you don't think you can cope with things going wrong, and you think you might be very angry with yourself, then that con will almost certainly outweigh any pro, and so you should not do it. Only you can make this decision. I was faced with this same difficult decision many years ago...I broke the device that I opened, but I was not angry, I was intrigued, and I strived to find a way to rectify my mistake. I found a way to fix the device, and I continue to open things up to this day. Good Luck!

It's possible that the repair technician isn't as skilled as you were hoping him to be. These repairs can be quite difficult, especially for beginners, and it is not uncommon for a device that has been repaired to have slight imperfections like the one you describe. It's difficult to tell if this is down to negligence without inspecting the repair work, however you should expect this kind of result from technicians who are not Apple staff. Maybe the screen was not a genuine part, maybe it was but was damaged a little and they didn't notice, maybe your iPhone chassis was damaged when you dropped it and that's the best they could do. Most repair services have a warranty on their work, if your not happy with their work and you want your issue remedied, you should seek legal advice if they do not comply.

The digitizer is faulty, or the connector is not seated properly.

Sounds like a defective replacement screen, iv'e had a few bad ones from eBay. Try unclipping the screen from the chassis and see if the lines disappear. Also try reconnecting the cables giving them a clean with isopropyl if you have any.

The battery can be replaced yes. You can watch a tutorial on how to here. It looks easy. You can pick up a battery on eBay for less than £10.

Rice does help draw out the moisture, however, before doing that I would recommend opening the phone and cleaning the internals with isopropyl if you can, otherwise the water will start to corrode the components and you might have further issues. Until then, do not charge the phone or power it up until the rice has done its job. Good Luck!

Don't tap it, whack it! Watch video below for demonstration. Black Screen of Death Fix

I had the same problem with a different printer on Windows 8.1. Try unplugging the printers usb connection and plugging it back in. Press the start button, and type "devices and printers". That should give you a link to the page your looking for.