For a temporary solution to an unresponsive on/off button, take and squeeze the phone between your thumb and index finger on the right or left side of the receiver (ear speaker), while you press the on/of button. For some reason or another the on/off button will work, while doing the squeeze.

Give it a try, worked for me.

This sounds silly, but mine had the same problem, and I blew very hard through the switch, just like a straw, and it started working fine. It probably dislodged some grime. Give it a try, nothing to loose!

I have the same problem. I took my switch apart and will try to clean it (mine was dropped in water by previous owner).

If that don't work, a new cable harness (including the switch) costs £4.99 on eBay UK (seller phaetondvip88 - I've bougth from them before and are very satisfied). The harness is labeled as 'Apple iPhone 3G Head phone Audio Jack Flex Cable' in their shop...

But, I'm going to try clean it first... Just need to go out and buy some 'electrical cleaning solvent' or whatever it can be named :)

I've now replaced both the battery and the button harness I mentioned, but still no go. I can't turn the darn thing off (!!) and I have no idea what can do this other than the button itself!!

I'll try Marks idea as soon as I'm sure that the battery is fully charged.

If Your Jail broken Find SB Settings Cydia the pull down is similar to the Android's pull down and you can turn off your device from the Menu. To turn on again just pug your charger in to the Port.

(my iphone got wet and im glad it works now) my power on off button does not work. Ive tried the hard rebot and it does give the the slide to power off BUT if i do this will i be able to hard reboot to turn it back on?

You can turn the iPhone off in the settings..

http://www.youtube.com/watch?v=6jNRlAlFR...

Success!!

I completely took it apart again. Removed the display assembly (but not separating this), mother board and sync connector. Cleaning everything by blowing clean, compressed air (from a aerosol can) in every nook and cranny and trying to get air in between the mother board and the RF sheilding from all directions, blowing everywhere on the back case and on and around the buttons (that where still in the case) and on all connectors (both on the mother board and on the flex cables).

Then assembled everything again, making 100% sure that all the connectors where correctly seated. Turn it back on and loo and behold! Everything works like a charm!! I can turn it on and off, I can enter DFU mode and it doesn't reboot as soon as I unplug the sync cable!! Dang, I'm a happy camper now!! :D

PS. Just in case this haden't worked, my next attemt would have been to spray/use some 'electronic cleaning solvent'.

A temporary fix would be the gesture button.. Go to settings>general>accessibility>assistivetouch and turn it on. Then when the button shows on your screen you press it, then go to device and press and hold the lock screen then the power off device will show so you just slide it over to power off device. To turn the device back on you just have to plug it into the charger...

My process:

1. Remove on/off button and press the metal pad to see if it works (then the button has worn out) - the metal pad sits under the button itself
2. If metal pad does not work, check that it is making a clicking noise -> remove pad and clean the contacts (sometimes they can be dirty)
3. If that doesnt work you need to replace the flex ribbon cable which is challenging the first time but pretty easy when you figure out the tricks

Dear sir:

1) The main switch can be faulty. However you must test it for open or faulty with DVOM and replace

You must try to clean the contacts with c.cleaner from sirty, corroded, tight the connector very well and clean it.

2) See the diagram attached, clean the main board from corrosion, debris, and bad contacts. clean it very well.

God bless you

Ernesto Cuadra

Managua, Nicaragua

For a hard reboot, keep pressing the power button and the menu button ( the big round one) for several seconds!