Take it back to that guy; he may or may not have done something wrong but IMHO he
should be the one to determine that (and make it right if it was something he did).

You should at least call him up and tell him the situation, maybe he'd even go out to its
location and look at it....

I had a burglar alarm professionally installed in a car once, a few weeks later the thing
started making noise all the time, even while driving. I brought it back to the installer,
turned out some wires had fallen onto the exhaust manifold, gotten hot and shorted out.
Don't remember if it was his fault or not but he fixed it for me.