Mine is the 2nd one, the "ghetto" one, lol
mine does it by the key (but is also switched so i can have it stay off). Mine also shuts down via the key. I have it to startup after failure, but if you have the system shut itself down it doesn't repower up until a power loss, and than a regain of power (ie inverter off, back on).
I would, however, recommend a commercial shutdown controller over a diy (after doing one).