After system is up & running
Unsecure wi-fi: I would assume you don't go over and borrow your neighbor's bar-b-cue grill, mower, drink beer, car w/o asking first. This alone answers your question w/o further details. Thus, you would secure your wi-fi once active again.
As for SBC, ask for new parts or describe your system broadband isn't working. SBC, has if you didn't know gone to another owner besides AT&T or is AT&T. They have shipped new replacements as older equipment didn't like the new s/w being used. I knew some users who had constant security concerns and they did do proper set-up, and SBC had to re-issue PW and etc. to get them back-up. That all went away after new equipment.