BTW, it doesn't hurt anything to shutdown via the fire handle - we regularly do that during functional testing to make sure the circuit works. However it is important to then place the fuel switch in cutoff as well.
There was a case back in the early days of the 747-400 - at the end of a customer acceptance flight, the customer pilot reached up and shut down all four engines via the fire handle - then pushed them back in without setting the fuel switches to cutoff. That re-introduced fuel into the still spinning engines resulting in massive tailpipe fires and ended up overtemping all four turbines
