Archos 50b Oxygen stuck on startup screen

Hello,
I'm french , sorry for my bad English.
My phone is stuck on the startup screen. (Rest loop)
I have already tried the recovery of origin but I 'm getting an error
"invalid partition settings " .
I search the image SP Flashtool compatible with my phone.
I have contact Archos but I 've no response from them.
All ideas are welcome.
Thank you!