This is a quote from a National Library spokesperson (Straits Times, 16 October 2008), after a disgruntled library user, angry that his illegally parked bicycle had been chained, locked the main entrance to the library.
Let’s consider this sentence: By locking even one door, it inconveniences members of the public.
It doesn’t work for structural reasons. First, by locking even one door is an adverbial of cause/reason. If we move it, we get It inconveniences members of the public by locking even one door — which shows more clearly how bad the original sentence was.
Second, what does the subject it refer to? Most definitely not the non-finite clause before it. Hence, make it: By locking even one door, one inconveniences/you inconvenience members of the public or Locking even one door inconveniences members of the public.