The following sequence turned out to be useful after a power-off-on to reset a controller that couldn't be operated by a Tango server:
$ telnet ipAdress portNo Trying NodeName Connected to NodeName Escape character is '^]'. :RS :SH :TE :TP :^]
The ipAdress and portNo can be found in the properties of the Tango controller (GalilDMCCtrl class device server).