Since everthing is working now (except the display) and I have full access to the filesystem with ssh - I 'm asking myself if it is practicable to substitue the defect N770-diplay against a SDIO-controlled handy-display. I ' m using Nokia 3310, 3510, Siemens 65 displays with microcontrollers (AVR and PIC) and i have all the nessesary glib-files for control. Also I have two old Zaurus SL5500 displays laying around, a N770 scheme and skills to solder SMD.
How much work would it be to connect one of those displays to the n770.
Otherwise I could serially log the /dev/ttyS0 terminal on a microprocessor controlling one of the mentioned displays. This would be easygoing for me.