Hi!
I think you should read this topic :
AF280T problem: Pentax SLR Talk Forum: Digital Photography Review
I started it when my AF280T arrived and it wouldnt charge.
Now it works almost perfectly. Everytime i wanna turn it on, i have to turn it on normally and let it there for 5 seconds, then i have to push the switch in order to get it stuck between the two positions, and then push it to on again. Then its on
Its weird, but it works everytime. I'll try to clean the button to see if i can solve this