two guesses (not fact just an opinion),
Bad news -> trub from the hot break leads to increased mass at the bottom of the jar not all of it might be yeast??? A guess, did you allow the starter to settle before decanting into a second sanitized vessel? I only do this if I'm building a starter from slants otherwise i get a lot of accumulated trub. Has there been any bubbles rising through the solution at all? I know if I'm worried about a brew/starter I'm constantly checking it, at the annoyance of my wife!
Good new -> live yeast is white, dead yeast is brown? yours look really really white, sitting on top of trub
If you have time (minimum 24hrs), you could wash the yeast (or a rough approximation) if you put it in the fridge for as long as possible (12hrs min ideally 48hrs) to make the yeast drop form suspension, then decant the used solution on top of the container leaving about 1 inch on top of the yeast, swirl the yeast and trub into solution. Allow the mixture to sit for about 10-20 minutes or as soon as you see the brown trub start to settle out then decant the yeast solution off the trub into new wort. This is the process I have been using to step up from a slant eventually I have enough yeast for brew and it is really active normally finishes eating the sugar in the wort inside 12 hours or some of the initial stages using baby food jars there is beer on the ceiling when I crack the seal.
Clem
P.S. I think there is about 20 people on this forum who's yeast also got a bit warm on shipment this week