MAKE SURE BATTERY IS FULL

make sure you put the kernel file into the maemo flasher folder on pc in windows it usaully c/prgramme files/maemo/flasher3.5

turn off n900 and hold u button on keyboard , connect the handset to the pc , a usb symbol should appear in top right of phone screen

on windows run maemo flasher as admin then run the command

flasher-3.5.exe -k zImage-800mhz -f -R

(please note that youll have to change the zimage-800mhz to whatever kernel your using ie zimage-900mhz or zimage-700mhz)

it should take approx 10 seconds max

make sure you put the kernel file into mameo flasher folder on pc so the flasher can find the file

PLEASE NOTE YOU DO THIS AT YOUR OWN RISK AND THERE ARE RISKS INVOLVED , PLEASE DO RESEARCH BEFORE FLASHING YOUR KERNEL ON YOUR N900 AND ONLY DO THIS IF YOU ARE SURE YOU KNOW WHAT YOUR DOING , IF YOU DONT I ADVISE NOT DOING IT AT ALL