I swear my Dexcom did not get wet!

I went running last Sunday like I always do, and wore my Dexcom in my running top on my left side a little bit below my left shoulder. I wore it with the screen facing outward, like I always do. The weather was sunny but in the low 50s and I wasn't sweating much at all. At almost the end of my run I got a low alarm and took the receiver out of my top. I pushed the button to stop the alarm and noticed the screen looked foggy. I held it in my hand, rather than putting it back in my top, for the rest of the way home (which was probably a little under 2 miles). When I got home, the receiver screen looked like it had water inside it. I left it in the kitchen and didn't touch it. About an hour later, I hit the shutdown button.
I just plugged it in to restart it this evening (5 days later) and the screen is pretty much un-usable. looks like it has water inside the left side of it. The rest of the screen lights up but it has horizontal lines all over it.
I called Dexcom support and the girl barely even let me finish before she said it had gotten wet and therefore they would not replace it under the warranty. I just got this receiver in December! :( I asked her how could it have gotten wet and she said any little bit of condensation can affect it. The thing is, I have run with other, older receivers and sweat a LOT more than I did on Sunday so I don't know if it was sweat/condensation. I just don't understand how this happened and I wish they would be more accommodating. I wish the receiver was not so sensitive to moisture. The girl on the phone recommended wearing the Dexcom armband with the receiver when I run. I never wear anything like that and I generally would not like to do that, but I am willing to try it. However, in response to my question of whether the company would replace it if it got sweat in the armband, she said it would depend on the circumstances. I take that to mean no.
I'm pretty annoyed with Dexcom right now. Wondering if there are any reasonable sensor competitors out there. I really hate running without a CGM but I don't want one that's so finicky.
Thanks in advance to anyone who can offer any feedback/suggestions on this!