About 1 week ago, I accidentally let the battery in my main N900 go dry. Whenever this has happened in the past, I've had a bit of a struggle getting my N900 going again, but this time I'm stymied. I have two N900s and 3 N900 batteries, and I can't get either to boot. When I plug in the USB cable, the LED on the bottom left blinks amber, pulsating at the usual rate. Eventually, the LED changes to solid green. Pressing the top button does nothing, however. If I reconnect the USB cable, the vibrator buzzes and the Nokia splash window appears (with no backlight). After a few seconds, the pulsing white dots appear, with backlight, and then they fade away again after 10 seconds or so. Nothing else happens. I've tried charging with a USB cable from a computer and with the Nokia charger. The results are always the same, regardless of the N900/battery combination. Does anyone know what's wrong? Do I have three bad batteries?

Thanks for any suggestions!

It sounds to me like the charging part is fine. Whether the battery will hold the charge is another question but at least the charging behaviour is as expected. The problem is turning the device on. Let's start with the obvious. You need a long press on the power button to turn it on. I am sure that's what you did but you did not say so. If that still does nothing, then the problem may be in the button. But all is not lost yet. You can make it start using the flasher. IIRC, the magic incantation is flasher -r.

Yeah, I certainly did push the power button for a long while. No joy. The odd thing is that *both* of my N900s are doing the same thing, and they both were operational a few months ago. I normally keep the spare powered-down, but i have been booting it every few months to sync it with my active N900. If it's an N900 problem, then they have both failed in the same way at nearly the same time, which seems unlikely. Both devices feel like they have intact USB ports, but I don't know if that means anything. It seems more likely to me that all of my batteries have gone bad rather than two N900s dying in the same way at nearly the same time. But perhaps I'm too optimistic.

@Ken
I would guess all batts down (but unlikely even yoi did not take care of them ). As chance both N900s broke is there but even more unlikely. Did you store your spare with battery inside? (high chance of drained, too).

I would try a full ppwer cycle before/after charging (shut down, batt out, push power button a few (10) seconds, batt in, boot) but as said I guess batteries drained (even your description in OP would tell me everything good ).

Best chance get an external charger (a 5800 or something cheap chinese universal like YIBOYLIAN AD-04) and try again after charging outside. Or just get a fourth one to check (not preferred)?
Or even better check capacity of batteries (simply voltage after charge and after startup try/tries).

Do you have the original charger or something else? For example, if you try to charge N900 using laptop usb-port, the device will stay in strange reboot loop for forever. N900 needs around 1A to start properly.

Ken says he has three batteries but only two phones. That means that at least one battery must have been stored out of a unit. A battery stored inside a unit, even seemingly switched off, would eventually drain and possibly die but a battery stored outside should not, unless it was stored depleted to start with.

Perhaps a thorough investigation is called for? Put one N900 aside and ignore it for the time being. Try all three batteries in the other unit. Then swao the units and try all three batteries again.

When I have this issue, I switch on the usb computer charging mode or I use a mural generic battery charger at least for few minutes and it generally solves the problem.

Amazingly, after more than a week of being on a Nokia charger, one of my two N900s came back to life today. Thanks to all who offered suggestions!

That would suggests a battery problem after all. Whatever the cause was, congratulations!