How change logo ".nb0":

Spoiler: METHOD 1
METHOD 1 (800x440 pixels):

1. copy picture with name "logo.bmp" to SD card (max. 2GB) and reboot

24bpp (true color): size 800x440 pixels !!!

2. delete "logo.bmp" from SD card after change

Spoiler: METHOD 2
METHOD 2 (800x480 pixels):
1. open picture in GIMP

any color depth: size 800x480 pixels

2. save picture as BMP 16-bit (RGB565): FILE-> SAVE AS -> WINDOWS BMP -> SAVE -> ADVANCED SETTINGS -> 16-BIT -> R5 G6 B5 -> SAVE

3. delete first 70 bytes(header) from saved BMP... (source: 768070 bytes -> result: 768000 bytes)

4. rename file to "logo.nb0"

5. copy "logo.nb0" to SD card (max. 2GB) and reboot

6. delete "logo.nb0" from SD card after change

Credits:eidamo