Thanks all of the repliers !
dbxr2r, my MP4 isnt the same as yours and I have not wall charger (only USB)
Here is mine:
In fact I think tadad1 was true when he told that this was probably due to a defective battery chip.
So I send back the MPX to the vendor. HE send me back a new one. But the protective glass was broken. so I tell him and then he send me back TWO protective glasses.
The overall process time was completed in very few days.
I have to congratulate this kind of seller. Very pro, réactive, speed and..... polite !
If I can suggest this examplary french very good ebayer seller its him:
Infosboutique
He is really based in France and send from France. And his prices are competitve comparatibely to china based vendors.
(if I may not recommend vendor, I pray the admin to edit my message but this is not spam or ad. This is a true recommandation.)
Sincerely yours, JL