I can't flash my n900 ..
when I write
"sudo flasher-3.5 -F RX-51_2009SE_21.2011.38-1.003_PRD_003_ARM.bin -f -R "

and press u , .... etc
the device turn on the orange led and did not turn

Anyway when I press power bottom it did not turn on ..

sorry for my poor English ...

once my n900 got bricked and i couldnt flah it by my own. i gave it to a repair shop. that man just flashed by different method. by connecting something on the back of the device under the battery. sorry for this posting here but i wanna know that thing.

This happened with me several times.

The only solution was to change the n900 battery just during the reflash procedure and after that you can use the old battery again.

If you don't have another n900 battery just use any nokia battery that fits the n900. For example I use the nokia 6303 battery just for reflashing my phone (but in this case you must stick the battery by your hand to the phone because it is smaller than the n900 battery and will fall down if you didn't hold it by your hand ) and after finishing the reflash i put the n900 battery again and everything goes perfect.

The guy above that said that he took it to a repair shop and and that something was connected to the back of the phone is probably the same issue of battery problem but the only difference is that the repair shop is more professional and doesn't use an old 6303 battery.

Thanks for your replys guys ....
@Virtuality I thinked the battery is the reason

Note: I am not saying that your n900 battery is out of use. OK
I am saying that whenever this situation happens with you just use another battery to reflash and then after that you can use the same n900 battery you where using.

So you don't need to replace the battery you have with a new one.

If your battery is too low, you won't be able to flash the device. Try plugging in the wall charger. If that fails to work, then you need to use a standalone charger or try another compatible nokia phone to charge your battery (search these forums and there are a few listed elsewhere).

@mukesh the device you're describing is a flashing jig:

Yup. It's really, really important to charge battery to >80% before reflashing.

Reflash the eMMC first, then reflash the Fiasco. Do not reboot in between (as per wiki).