Q: Wireless keyboard won't turn on after changing battery

Your lucky! I tried 3 sets of non-rechargeables and none of them work.  I tested the batteries and they are good! 

I'm thankful I have a wired keyboard as well, but refer the wireless.  I'll take it in and see if anything can be done

without spending the cost of a new one!  If it can't be repaired, I will NOT replace it. 

I had this happen a couple weeks ago - new batteries  - keyboard won't power on. So I took out the batteries and rubbed both end points inside the battery slot and the screw button inside surface with a pencil eraser even though they looked clean to my eye. I then reinsurted the batteries , pushed the power button and got the green light all was good in the keyboard world again! Hope this works for someone else - I was just about ready to spend $50 buying  a new keyboard.

If you are having problems with getting an Apple Wireless Bluetooth keyboard, mouse or trackpad from connecting to your Mac (iMac, Macbook or Mac Pro), you can try this. The following mentions the keyboard, but it should work for other wireless devices that have a on/off switch of the contact type (i.e. press on and off, rather than a physical slide switch).

1. Switch off the keyboard by holding down the power button for at least 3 seconds
2. Click the Bluetooth icon in the menu bar
3. Click on “Open Bluetooth Preferences”
4. Your keyboard name will be displayed. Two-finger click on it and select REMOVE.
5. Once the keyboard has been removed, turn on the keyboard by holding down the power button, BUT DO NOT LET GO OF THE POWER BUTTON. It must be held down through the entire process.
6. The Setup Assistant will find the keyboard, so click the name of the keyboard, and then click on “Continue”. Make sure you are still holding the power button down.
7. You will be prompted for the Pairing Code. Type the pairing code on the keyboard and then press return. There will be a slight delay whilst the pairing completes (a few seconds)
8. The keyboard will now be Paired. You can now release the power button.

So just to clarify, the trick is to continually HOLD DOWN THE POWER BUTTON.

The trick of tin ball continues to work very well, thanks all!!

If you keyboard will not power at all, try to stick something down the batt compartment and scrap the grey thing on the bottom. It worked for me

I just got this problem today too - turns out to have been a little oxidation on the + terminal inside the case.  A quick scrape removed this, and keyboard now working again.

I have the same problem, will try this trick.  Thank you

Ok,

Same story here. Left the KB catching dust for a while, and then it did not turn on again.

Brave as i was, i decided to kickstart the keyboard again.

So, i reversed the batteries and pressed the on/off buttons for a couple of times.

Then i reinserted the batteries correctly again, and zapp!... it works again!

ATT: try at your own risk. It worked for me. Might be for you. If nothing else works..

My keyboard just died in front of my eyes, literally disappearing from Control Panel as I was trying to set it up. Brand new batteries. Tried putting them in again etc but no dice, so I folded up a square of tin foil as suggested and dropped it down the tube and hey presto, keyboard back to life.

I can't believe it. To be honest I thought you guys were crazy suggesting the tinfoil trick. But after having tried everything else, I decided to have a go.

And voila! I have a working keyboard again ;-)

Thank you for this twisted solution !!!

Same Here!

At first I thought no way tin foil?

take half an inch square piece of 'tinfoil' squeeze it into a little ball shape, drop it into the tube, put the batteries back in and at least mine works works like a charm again

thanks a lot for this tip

I had the same problem: the Apple wireless keyboard stopped working after replacing the batteries.  After a couple of days of playing around (and, yes, buying a new keyboard - which I will now return), I discovered the problem.  It was not with the keyboard or the batteries.  It's that, when people change the batteries, they often (and uknowingly) turn off the keyboard's power-button.  They do this - I did this - while attempting to remove the batteries from their compartment.  I didn't know - it's not obvious - that the keyboard  has a power button.  It is activated (On and Off) by depressing it (slightly).  The button is on the side of the keyboard.  It's the round thingie at one end of the compartment that contains the batteries.

I hadn't intended to turn it off - and didn't know that I had - when I replaced the batteries.

To "fix" the keyboard: I pressed the power-button on the seemingly defunct wireless keyboard.  Green light flashed.  The keyboard probably worked at that point, but I didn't check to see that it did.  What I did, instead, was to shut down the computer and unplug the recently purchased (and, happily, now superfluous) USB keyboard.  Then I restarted the computer.  The wireless keyboard worked fine.

I had the same issue with one of the older Model No. A1255 keyboards.

What I did to get it working was:

1. Open up the bluetooth console in system preferences.

2. Look for and delete the paired keyboard.

3. Turn off bluetooth for about 30 secs or more and turn back on.

4. Press the power button on the keyboard, you should see the keyboard pop up in the list and get a pair option out to the right.

5. Hit pair, then type something on the keyboard. (I typed 0000).
6. The pair code should display on the screen, type the code on the keypad.

7. The keyboard should now be paired.

Hope this helps someone.

AMAZING! i bought two pairs of different batteries 'cause i thought apple was just being funny with the ones i had, still didn't work then did this.  voila! magic.  I'm so happy, thank you!

I just did this to a keyboard that would not turn on after correctly installing new batteries and all these years later, this solution is the only thing that worked!