Thanks. Not everyone is American, and know what shops to google. I had tried radio shack with no results - but will try the other suggestions now.

I installed a GPS program (sygic - no battery indicator I could see while driving). This is the first time that I have used the phone with display on pretty constantly and with sattelite\gps for 4 hours.
The phone was relatively warm before this happened.

Batteries Plus has an aftermarket battery by Rayovac (I think). It doesn't have quite as high mA rating, but I picked one up when my Nokia battery started acting flaky. It seems to last about as long as my original Nokia battery did, but I've never done a direct comparison. Google Batteries Plus and see if they have a store near you.

Bright yellow means emergency charge, battery is too low to boot the system and start normal charging.

What do you mean by flickering? If it's doing a short flash every second or so, it's a repeating error condition. Could be battery or charger gone bad.

I think there is a shop called Jons Mini Mart 7-11 near Daytona Beach. It's on Parrock Street if my memory serves me correctly, but i might be wrong.

Getting a new battery should fix your problem since it won't be completely empty by default. N900's battery is common so just go to a shop and get one. However, it should be pretty easy to get a wall usb charger. It is included in some travel kits for phones.

If your battery is empty then the phone cannot power itself. For usb charging to work, the phone needs to negotiate with the usb host to get some power, which is not possible if the phone has no battery at all. AFAIK that's why you need a charger. However, if you have a powered usb hub you can try using it without connecting it to a pc (or leaving the pc off). Some hubs give power when they do not operate.

Finally, just for testing, try removing the battery and the sim card and re-adding only the battery.

*** Updated the OP***
Hi everyone, Thanks for your help so far. Here's an update - help still needed.
Bought new battery - tried to start N900 and didn't get past the screen with Nokia in blue on white background. Thinking the new battery might not be fully charged I left it charging all night, this time back in my home country ith a wall charger - and now the second battery is empty also!

I now assume I will have to reflash - but before getting a third battery or an external charger - I want to make sure it will work. When I connect the phone to the computer via usb I cannot see the n900 as a flash drive. Does this mean I won't be able to flash?

Are you familiar with the flashing process in general -- have you flashed before? If not, you may not realize that the usb symbol only appears momentarily unless you are following the flashing documentation very closely.

Flashing almost always works, once you understand exactly what you need to do, and are set up correctly. The main obstacle would be if your usb connector is damaged for some reason. Then you won't see evidence of a usb connection because there isn't one.

Did you try removing the sim card and starting the phone without it?

tried that. doesn't work.