My Polder is about a year old.
It just decided that temperature is no longer of any significance

I plugged the probe jack in the unit and shoved it into the grain sitting in my Tun Sans any strike water. The Polder thinks it is 110F in there.
It's room temperature The grain has been sitting in the room for a couple days.
I swapped out the old battery for a new battery.
Still not working right.

Back to the old school thermometer I guess.

I had that happen to me before. I think it is because I got water in the probe and is conducting the current better giving the high reeding. Though you can never go wrong with the glass ones unless you break the glass itself.

Well on the thesis that maybe moisture is the culprit, I popped the thing open ( It's got little screws) and took a hair dryer to it..

Now it's as steady and reliable as it ever was.

Lesson: Don't toss your thermometer away. Give it a rest in a nice warm dry place. Maybe a little nap will dry it out and save it.

Should never use glass in a home brewery. Drunk people and glass don't mix!