so many posts about flashing, yet no one has searched or gave him instructions on how to do it

turn the phone off, take the battery out.

download flasher from here
download
download latest firmware from here

save when you have installed flasher move the firmware in the directory where you install mameo flasher. c:/programfile/maemo flasher.... where ever it installed it.

open cmd and type
cd "%ProgramFiles%\maemo\flasher-3.5"

then
flasher-3.5.exe -F RX-51_2009SE_20.2010.36-2.203.1_PR_COMBINED_203_ARM.bin -f -R

(change the bold writting to match your filename which you saved in maemo flasher directory).

now it will say waiting for a suitable device.
plug you usb in to your phone. hold the "U" key and put the battery in. Keep holding the "U" key until it starts flashing the phone

good luck