You could have multiple failsafes, and after a part of them fail, you dehibernate automatically. We have systems that work well with such approach - planes being the most notable example - multiple redundancies, and when sth critical fails, you land asap. Works most of the time.
You what now? :) I think you watched too many scifies and started to believe that the plot devices are reality. “Hybernation” is a thing in movies because the writers wanted to write stories involving humans and long space travel. It is not a working technology in reality. It might become one day, but your RTG powered cocoon is not going to invent and perfect it for you while you are asleep.
And then you wake up on the moon in a lava tube too early with a partly failing system and hope that everything else still somewhat works? With current technology level I definitely would rather bet on humans.
Looking at current human society, I don't think that's a very good bet.
If you wake up too early in a lava tube on the Moon, you then use the tools and spare parts you hopefully were smart enough to pack and repair your cryo-pod and then go back to sleep.
