IPhone 3GS - Full hard reset does not work. i have a black blank screen and nothing works?

Try to bring the phone in recovery mode and make a fresh install of your current iOS with iTunes. Connect the device via USB to your computer and turn it of (when possible) with the power button. Then press the power button for 3s. After 3 seconds press the home button for 10s while still holding the power button. After 10s release the power button while still holding the home button for an additional 10s. The phone should then be in recovery mode and iTunes wants to reinstall the OS.

Hope this helps.

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Frozen or unresponsive iPhone

Mine just started doing the same. Starts up and shows apple symbol, then goes to black, then crashes and repeats. Completely un responsive and my computer won't connect to it because I have to unlock the phone. :/ Reason it is doing that might be because I only use iCloud for backing up.