Well, we don't believe there is such a thing as a stupid question. However there's probably no way anyone here can answer it!
If the installer grabbed a power source from the cruise system,they may have altered something. If they disturbed a harness, temporarily moved anything, accidentally blew a fuse, or whatever, they may have affected your cruise system and would not know it.
On the other hand they might not have; your cruise system might have an unrelated problem. Either way, it could be a long process to get to the bottom of this type of problem. Best of luck!