1 - dissaembled the N900
2 - pressed with a screwdriver on the metal hedges that are under the shutter button, pressing them a bit more firmly into place
3 - took a q-tip, richly dipped in 96% percent alcohol from the drugstore and dropped some of the fluid around the lens and dipped the part of the motherboard with the shutter button in a cup filled with the liquid.

4 - put it in a box of rice to dry.

5 - being impatient, put the oven on 100 degrees celsius and stuck the motherboard in for 5 minutes (above 130 the plastic keyboard
and the plastic connector around the camera system can and will melt)

6 - took it out, burned a finger, let it cool down

7 - reassembled, stuck a battery in, boot, start camera app

8 - miraculously it works again.