thank you for all info.
I examinate the makerbuino “broken”.
Finaly I think it’s not a solder join problem, but a sdcard adapter µSD to SD contact problem.
F2 contact inside the adapter and I press the SDcard holder, to make mecanical constraint, and now I think it’s OK.
But I swap the ATMEGA328 from “broken” makerbuino to a “new and good condition” makerbuino.
On the “new and good makerbuino” ON+C trick not working -> After several minutes the screen still blank screen.
And the ATMEGA from “good” to “broken”, no problem I can play with “broken makerbuino” ! :slight_smile
Conclusion, I have a ATMEGA broken (or lost bootloader?).
It’s easy to reprogramm or clone ATMEGA with arduino (or other easy and cheap way)? I’m on linux.