Wow, you're are faster than light!
Thanks to fe50 and casrap for all the work!
But sadly the firmware doesn't work as intended...

I've used the "LICKS"-Java-programm to format (FAT16) and copy the data from the full package. I hope that I did everything right. - If you want to check; there is an image of the sdcard that I'm using
here (756.0 Kb/2.0 Gb).
If the cam is started (lock to "on") there is a very short time of displaying build number, date and target "A3100 100a" - most times only partially - and then the cam just switches off, independent of pushing the buttons play or on. If I push "on" long time the lens starts to move but stops suddendly - next cycle I've got quite disturbing sounds from the motor/gears. I can also activate the clock by pressing func on start up - lasts about 2s before shut down, too.
Anyhow - If I put the lock to off, the cam starts normally.
Are there any special bits to activate some kind of "crash message"? I had understand that the "update firmware" method needs another build, could this show some additonal information? The DISKBOOT.BIN of 100a is quite smaller than 100d. Is this ok?
Thanks again and greetz!