I need to reset the old unit in home has old tenant passwords and is not connecting
Can you provide more information? type of panel, etc.
Looks like this is regarding a 2GIG GC2 that was registered for a new account.
Do you have any user codes for the panel?
To successfully activate the panel you would need to run a cellular communication test from the panel. This can be done with either the master user code or the installer code.
Did the prior owner not provide a code?