It would seem a couple of us are having the same issue. That is, the n900 powering on as soon as the battery is inserted. At first I thought this was due to a dodgy soldering job I did on the USB port however it seems other people are reporting the same issue with 1 person having not soldered the USB port.

Which of the people who are facing this issue are using cssu-thumb?

Does setting RD flag 'power_button' actually workaround this problem?

I'm having that isue on one of my devices, without having messed with the USB port, ever. I'm using latest thumb. However, I'm 60+% sure that behavior appeared before I switched to thumb on that device.

It should happend only when the N900 is in RD mode

Mine defo is not (and never was) in R&D mode.

Edit: Ok, in R&D mode it still boots when I insert the battery (apparently just as it should), plus it actually boots up fine (no loop), plus I can't switch it off anymore (reboots instead).

Removing R&D flag reverts to old behavior (boot on battery insert, boot loop). Kinda expected...

@vi_

I also have (had?) that with my dev-N900. It happened during the time when it bricked and I desperately tried to fix it.

Two (wild) thoughts:
1. N900 gets electrostatically charged, making it do weird things.

Reason: during my attempts to flash (or even to set R&D mode) on that N900, I booted it many times by connecting the charger without a battery in place. It behaved very weird. It entered flash mode (NOLO), but the computer didn't notice a thing. Also the microSD card didn't work.

After leaving it a couple of months in a drawer, without the battery, I managed to unbrick it using the same method I had tried before (OK, this time I used the set_omap_atag or whatever the name was when booting from the U-boot console).

After unbricking it, charging worked again (shaky, but it did), and I was able to set R&D mode using the flasher (so USB works after all).

2. If you take out the battery while not really off, but ACTDEAD, it could be that reinsterting the battery makes it boot automatically (e.g. so that you don't miss an alarm!).

Just two wild guesses. When I have the time I will experiment again with that particular N900, but AFAIK it does not boot anymore automatically when inserting the battery.

i've had this for quite a while now. It also asks me to set the time and locale settings each time after swapping he battery, just like fresh from the factory. That specifically I'd like to go away. I use latest thumb, but my device started doing this way before I switched to thumb, and now it still does. Never did anything to the hardware, physically.
i'm also in R&D mode, and I thought the boot-when-inserting-battery thingb was *because* of the R&D mode, so that would not make it go away. I'd like to get rid of this though, I find it annoying.

It only happened once to me once about a year ago. No cssu-humb, no charger, phone booted up on battery insertion. But I might have been pressing the RD key by mistake, I can be clumsy that way.

The reason for this is that the clock's backup battery is dead. No easy way to fix it, unless you're prepared to replace it.

Does anybody have an N900 with a working internal battery?
Maybe this behaviour is to do with this?

The clock battery of my wierdly-behaving device is still working properly.