Did I permanently destroy my MS250?

[TNsawman]

Disengage the brake immediately after startup. If you want the high idle to stay on for a few seconds to help warm it up, just disengage the brake in a safe way without touching the throttle. I prefer to find a safe way to start it with the brake off, then it's never a problem. I can always set the brake after startup if the saw is to be left idling just to make sure it doesn't start spinning the chain on the ground.

 

[dmb2613]

ms 250s are still sold new and will be for some time I expect, a lot of saw for the money.
And you can not warranty stupid. The dealer may have been at fault for not going over the start up procedure with the buyer, but it is all in the manual. Some people should not own or operate a chainsaw.