Answer

Please press the ESC button several times at the start of the boot procedure. Select the point  „verbose boot“ from the boot menu which subsequently appears in order to come to the Linux control panel of the Thin Client. There you can manually configure the device for the update.

Update with the aid of the control panel – Update parameters

[variable content] / > complete with Enter / _ represents a ringing tone.

Reading the update parameters:
nget update.ftp.server_[xxx.xxx.xxx.xxx]
nget update.ftp.user_[FTPUsername]
nget update.ftp.password_[FTPPass]
nget update.ftp.path_[Firmware update path]

Setting the update parameters:
setparam update.ftp.server_[xxx.xxx.xxx.xxx]
setparam update.ftp.user_[FTPUsername]
setparam update.ftp.password_[FTPPass]
setparam update.ftp.path_[Firmware update path]

Deletion of the update partition: igelinval_1 [2,3]

Start of the update process: update

or optionally

update_1/update_2...
 
for updating individual partitions.