iPhone keeps repeatedly turning itself on after i turn it off.
It also keeps randomly saying "This device is not made for iPhone"
even though there aren't any accessories plugged into it.
It also drains the battery in couple of hours.
Does anyone have a clue about this problem?

Sounds like you need to try a restore then use iLiberty to jailbreak again.

I am guessing your already on 1.1.4 unlocked so the unlock will remain even after a restore but you will have to jailbreak again.

If your not on 1.1.4 then upgrade and run iLiberty with the unlock.

That should fix the problem.

And DO NOT restore from a back up - set the phone up as new!

I've already restored and jailbreaked again.
And I don't think the jailbreak causes the problem, simply because before the problem I've been using it for a month. It was jailbroken the same way.
So, something else is causing the problem.

I've solved the problem!

Here is how, step by step:

1. Connect your iPhone to the Dock
2. Turn it off while plugged in the Dock
3. Leave it turned off while charging
4. After charging, turn it on while the iPhone is still plugged in the Dock
5. Disconnect your iPhone from the Dock

This worked for me. I hope the problem will not come back.
Try and please inform if it worked for you.

renamed thread and congrats on fixing it

Hi I have the same problem, and I tryed to solve it the way you sad. It turns off on the dock thats correct. But after turning it on and emoving form the dock the problem is not solved. It cannot be turned of than and the decribed behaviour is still there...

Any sugestionsto get it back to mormal?!?

I also have the same problem with my phone turning itself on unless I turn it off when connected to the dock. It also drains itself in a couple of hours. I have restored it several times without luck. Once I let it drain then connected it to the dock to charge. Then I could shut it off. However, when I turned it back on and played with it for some time and tried to turn it off again, the same thing all over again.

What I have discovered though is that If I put it in standby-mode (by pressing the sleep button) I can here static noise in the headphones. This is normal, and after a while it disappears and it becomes silent. However, after a few seconds, the static noise comes back, as if the phone starts up from standby due to some program launching (the screen statys black). This then continues ... static noise comes and goes. So the phone is never in standby for more than a few seconds.

I have tried to look for any programs running in the background with different apps, but I can't find anything out of the ordinary. And this still continues after restores, both regular and from DFU-mode. I have searched with google and on this forum without success, but it's good (or maybe not for you ) to hear other have the same problem.

iPhoneMK: Your trick seems to work for a while, then it goes back to that annoying state!

So I wouldn't call this solved...