Dead yeast and starter F.G.?

We have had five days of temps over 103*. My order from AHS shipped Monday and arrived on my front porch on Wednesday. It was in the direct sun and 104* for probably 30 minutes or so plus all day in the back of a UPS truck and two day shipping from Texas. The little cold pack was long past being cold. This is a partial grain Blue Moon clone with White Labs 400 Belgian Wit yeast. I put the yeast and Wheat LME in the fridge when I got home. Last night I made a starter and went to bed. No apparent signs of fermentation but no worries yet. Today I made the second stage of the starter and added it to the growler.

Can I take a hydrometer reading of the starter to check for fermentation? I am worried that the yeast didn't survive this heat wave. I planned on brewing this Sunday but obviously not without live yeast.

Sure you can do that. I've resorted to doing that when my starters seemed to do absolutely nothing. Luckily, each time I checked, they had fermented out or were just about finished, but it was good to know for sure.

Well the yeast is dead. Absolutely no activity in the starter. Went to the LHBS and bought a Wyeast 3068 Weihenstephan Wheat. they didn't have any Belgian. Now another starter. Maybe still can brew tomorrow!