Cannot access serial terminal / reinstall failed / EUD

I have a serious problem with one of our 2 big ip 3600 LTM I did a reinstall from an image located on the hd (10.2.3) with factory settings (no config backup).

On the first one, it worked well, but on the second one i get the "EUD" message on the LCD panel (maybe after a power failure during setup)

So i tried to resintall it from image located on a CD but it's impossible to access the serial console with the following parameters (i get garbage caracteres): Baud rate: 19200, Data bits: 8, Parity: None, Stop bit:1, Flow control: none

It tried with every baud rate, rebooting the big ip...same problem

It tried on the over BIG IP with same serial null modem cable and it works fine

So, it's impossible from me to log in and use serial console and to reinstall the failed big Ip from CD

Do you have an idea how i could access serial console or reinstall this big ip ?

Many thanks

Regards

Hugues