Pull the muffler and check for cylindler/ piston damage. When not properly tuned these saws will lean out and toast the PNC. Air head carburetors tune differently than other cubes. Plus using the saw when it was for much warmer air temp would cause it to lean out at 20 degree as the air is much denser.
You could also do compression test. If the starting compression is below 100 psi it is also toast.