Hi Derek, ah the mysterious ESC (Electronic Speed Controller)!
Ok I'll try to answer in order here...
First off, an ESC will just burn out for no reason, so probably nothing else to blame in that case.
But I wouldn't rule out maybe the motor itself also possibly having an issue with a high resistance to where spooling it up like that reared its ugly head and helped create the failure. The good thing is it happened on the ground and not in the air!
Secondly, I am pretty sure there is no governor setting in that particular "stock ESC" with the 450L.
The governor is a case by case preference of people flying heli's. All governor is really is a set steady head speed. And is basically how a real helicopter flies, a set head speed and varied by the pitch of the blades. Myself only within the last few months have started flying in governor mode. I've found that I am preferring this more and more to say a flat throttle curve that I usually ran.
You'll still use the flat curve in governor mode but your RPM, and head speed is more accurate. Without governor mode you may have say a flat throttle curve of say 80 percent, but that can vary causing a less smoother flight experience than with governor.
The esc's most use that have a decent governor are Castle, Hobby Wing, and a couple others that I can't remember right now.
I highly recommend a Hobby Wing though, while Castle and others have good governors they can be a pain to get set up. Where as the Hobby Wing is pretty easy and straight forward as well an excellent governor function!
Right now, if I were you I'd get yourself a 60a HW ESC as a replacement for the 450L (that's what I run on mine, 60a Platinum Plus v4). And just set it up without governor first. Get the program box (it makes it very very easy to set up). If your budget is tight a Hobby King YEP ESC is a good alturnative also, but get the program card with that, really any ESC you buy, if it has a program dongle or card get it too. Way way better setting up verses the old beep and stick method! I think Smoogie has or does use that ESC on one of his heli's, and another member named holtneil. The YEP has a good governor also, but is a little more involved to set up. If I were you though, I'd just set it up without gov for now whatever ESC you get. Just use a flat throttle curve for now. Just get used to that.
Finally the slow start feature that has to be programmed in is where your preference of how long the heli spools up in the beginning. I try as set mine pretty slow, I like to let mine slowly turn over. It's more like a real helicopter. Those spool up rates vary from ESC to ESC.
If you go back to the stock ESC, those are pre programmed, and they are to be programmed with the beep and stick inputs.
Although I couldn't tell you how to get into the program mode for a stock ESC, am sure if this is possible at all to do the info is out there somewhere on how to.
Hope this helps at least some....