Thanks for your support.
Hereafter the feedback after trying to upload a minimum sketch (empty sertuo + empty loop :
Sketch uses 12000 bytes (4%) of program storage space. Maximum is 262144 bytes.
Global variables use 2204 bytes (6%) of dynamic memory, leaving 30564 bytes for local variables. Maximum is 32768 bytes.
Forcing reset using 1200bps open/close on port COM8