Samsung Galaxy S2 can't transfer pics, shuts down by itself, does not charge

Question

My Samsung Galaxy S2 (not rooted) has all sorts of problems.

It started when I tried to take some pics today. I would take a pic, and it would shut down.

I tried to get pics off my phone by syncing it with my computer. The computer said the files had errors, and asked if I wanted to skip those files.

Then, the phone started shutting itself down for no reason.

When I turned it back on, it said low battery. So, I plugged it in. About 30 mins later, it said it had 100% battery (I'm sure it didn't). When I turned it on and tried to use it, it would act like it had low battery again and shut down.

Now, it's getting worse. I can't get it to stay turned on for more that 5 seconds. It shuts down straight away.

I could see that the phone still had the pics on it. I'm hoping it can be fixed, so I can take it to someone to try and get the pics off the phone. My new baby pics are on there as well.

Any ideas as to what it is? I'm hoping a simple battery change will fix it, but I'm not sure why it says it's charged when I know it's not.

Any help would be greatly appreciated. Thank you in advance.

**Missing details....

Thanks. Yes, I've removed the battery for up to an hour. I was originally charging on AC power. I had to use the phone after being charged for about 30 mins. It showed it had around 75% power. I went to use the camera, it shut off and when I turned it back on it showed very lowe battery. When I plugged it back in and turned it on it showed 90% power. When I went to use it again it showed low power then turned off. Turned it back on and it showed 60% power. I left it charging and in a few mins. it showed 100% on charge. If its on USB or AC power it will get to the lock screen. I can unlock it then it shuts down after 5-10 seconds. Doesn't matter if I'm doing anything on it or not. If its not on power it doesn't complete the start up sequence. Only gets to the start of the "music" after you see the "S".

Answer 1

^{This answer will be updated along the process. So for now, it just holds initial steps / a raw solution.}

There are several things you can try to get your device back to working normal. I will list some steps; just break as soon as anything came back to normal: in that case you will not need to walk the remaining steps unless the last step taken explicitly mentions something alike:

1. battery check
   1. take out the battery, leave it out for at least 30s (2min won't hurt, more should not be necessary).
   2. insert battery again, but do not yet switch on your phone.
   3. fully charge your phone on AC (not USB from a computer).
   4. switch it on again. If it's working now, everything's fine and you are done.
2. faulty apps check
   1. shut down your phone
   2. start it in "safe mode"
      (how to do that depends on the device; on the SGS2 this should be accomplished as follows: Press power and menu, then release the power key but keep pressing the menu button. The word "Safe Mode" will be displayed on lower left if I'm not mistaken. -- source: LowYat.Net; I have no SGS2 so I cannot verify)
   3. none of your self-installed apps will be started in safe mode, only system apps are available. Check if the behaviour changed (I guess not, but it's a good point to know for the last group below).
   4. while in safe mode, try to backup as much things as you can reach. If already on Android 4.0 or higher, see Full Backup of non-rooted devices for how to safe the most of your precious stuff, but better stick to separate small packages (backup on a per-app basis, as restoring the full package later might bring the problem back). On rooted devices, Titanium Backup is probably the best choice.
   5. this was just an intermediate step; even if your phone is working normally in safe mode, this will not have fixed the issue for "normal operation", so go on.
3. factory reset
   1. do a factory reset of your device (warning: all your data and self-installed apps will be lost from the device, hence the backup recommendation above; your sd card should not be affected, but it cannot hurt to copy all its data to your computer as a backup before doing the factory reset)
   2. startup the device again. Before installing all your apps again, make sure the issue has been fixed by the reset.
   3. if your device is back to normal, you can go on re-installing your apps / restoring your backups app-by-app. Between each app, make sure to test a while: if any of the apps was the cause, you might otherwise bring the problem back by restoring the "faulty" backup. If that happens, remember which app it was; start over from step 3.1. and ommit this app in the next run.
   4. if you've restored everything, and your device is still working normal: congratulations, you're done!
4. if the issue still remains, it has to be some hardware issue. Could be the battery is broken, so next I would go to your local dealer (best the one where you've bought it), and try with a "spare battery" from his store. Explain the reasons, including the results from the "safe mode check", and also that you've already tried a factory reset (because that's the first thing he will do otherwise). If the new battery solves you issue: buy it :) If not, next step:
5. If you still have warranty, send it in for repair (or let the "local dealer" handle this for you). Make sure all details (including results from the "safe mode check" and the fact you already tried a factory reset without this solving your problem) are included with the report.
6. if you don't have warranty anymore, ask the dealer what a repair might cost. It could be cheaper to simply buy a new phone...