chest freezer always running

Hello at RE:

I have a White Westinghouse chest (model: FC105L), it could be twenty years old.

To date it has worked perfect, even after being moved twice.
Here is the short history of the issue. We had a little storm pass through
CT a couple of days ago. In anticipation of the storm I turned up the freezer
and I bought 20lbs of dry ice. We lost everything in our refrig's and freezer two years
ago, in another storm. I put the dry ice in a small cardboard box, closed but not sealed,
on top of the food in the freezer and put a light blanket on top of the freezer.

Well we were lucky only lost power for six hours. This was actually guaranteed by the
fact that I ran around to find dry ice.

Now the freezer is always running, I can hear the compressor. The freezer inside is good and cold. I turned the freezer off last night and turned it on this morning. As of now, three hours later it is still running. I expect it will keep running.

So kind and wise RE guys and maybe gals. What did I break?
Is there a thermostat on this freezer that can be easily replaced?
I looked on-line and could only find a Temperature Control Part Number: PS425273,
for this freezer.

And now for the Lovely Mrs's question: Did the dry ice break the freezer?
Or did the fact that I moved the temp control which had not been moved in 10 years
break the freezer?

Many thanks for your attention to this matter.

KBD