N900 won't boot
 

yesterday i wanted to make a wifi hotspot using the joikuspot, but i couldn't find it oin web, so i installed the mobile hotspot.

but after installing it thorugh the program manager, i was unable to make it run. so i have uninstalled it. the same way.
then i have turned my n900 off to take the simcard out, but now, i just can't make it start again.

when i try to turn it on, it won't boot anymore. it keeps stopping in the white screen with nokia logo on it. i doesn't jump to the next screen with the sequence spheres blinking.

what should i do?

thanks for the help.