I just plugged it in the wall and it is charging again. Ram is all lost (made my last hotsync 2 days ago). The really weird thing was that my Clie was on the table and I heard a strange clicking noise. First I thought it came from my cellular but then it was my Clie! It never did that before. I took it close to my ear to make sure it really came from it
I then tried to turn it on but it wouldn't let me so I presumed that the battery was empty (despite it being at 4.12V yesterday).
Now that I am charging the Clie I can turn it on again.