Hi, this is my first post in this forum. I searched a lot but I couldn't find a solution to my problem.

The problem is this:

If I try to boot my N900 without a charger plugged in the following happens:

1. The phone immediately vibrates and a Nokia logo WITHOUT backlight appears.
2. After a couple of seconds the screen goes black.
3. The LED turns on in white, the slowly fades out.
4. The phone turns off and doesn't boot.

If I try to boot with a wall charger plugged in, the phone boots correctly.
The battery is fully charged, because if I boot with a wall charger attached, then I disconnect it after boot, the phone works normally for one day or two.
I also purchased a brand new battery, but I have the very same behaviour.

I noticed that also when I disconnect the battery, then I connect it again, I see the same behaviour described above (vibration, Nokia logo without backlight, white LED turns on and fade out). I can't remember if this is the normal behaviour when connecting a battery to the phone.

Another problem I have (maybe it is related) is that sometimes the N900 thinks to be still connected to the charger, also if it is not.
I see the yellow led blinking when the phone is locked, and I see the battery icon in the charge state when it is unlocked. Sometimes the phone leaves the false charge state after a while, sometimes the charge state lasts for hours, and the battery drains quite fast (maybe the phone doesn't use some power saving functions because it thinks to be connected to a charger)?

Thank you in advance for your help!

This looks like when i try to boot mine while the battery is "empty", i.e. the charge is not enough to fully boot. For example happens after the N900 switched itself off caused by remaining charge depleted, and you try to switch it on right after this.

What gives 'cat /proc/bootreason' right after booting with the charger plugged in? I'm trying to remember, i read something in the level 3/4 service manual this week....

~ $ cat /proc/bootreason
sw_rst

Thanks for the link, I'm currently downloading the manual.

Seems that early boot is getting wrong info about the battery. If You add strange behavior when it's running ("thinking" that it's connected when it's not, and booting up immediately after inserting battery - it's *not* normal), it may mean hardware failure.

Ho ever, have You tried reflashing, just to be on safe side? Also, flashing framebuffer kernel will reveal which part of boot *exactly* fails.

// Edit

Before trying to reflash or flash framebuffer, I would check if it act the same way with R&D mode enabled. There was a guy here, whose device failed to recognize raw BSI value. It can't be true in Your case, cause You can boot with charger, but I'm 99% sure it have something to do with detecting battery.

As R&D mode with watchguard disabled flag turn off watchdogs, it may permit phone to boot normally. Worth checking.

Maybe setting R&D mode to disable watchdogs and observe?

Can you tell me what is the flag to disable from whose listed in http://wiki.maemo.org/R&D_mode ?

Also, I don't understand why disabling watchdogs can help to detect battery correctly, can you give me a hint?

Thank a lot for your help!

no-lifeguard-reset

Is Your flag to go.

As for rationale - part of booting process use getbootstate binary, to get info about battery type inserted - regular, fake, testing, or unknown.

If, for some reasons, during boot Your system is detecting wrong battery, lifeguards may shutdown device. It's also possible, that battery itself is detected correctly, but it's voltage not, and device "thinks" that battery is empty.