Yes, I have tried restarting ES. After a while, it prints this error in the error log and terminates. Googling around suggested that this error occurs when the translog is corrupted.
The full log is 170 Kb; I cannot paste it in a message here; there is a restriction how large a message can be. I've put it on Pastebin, there.
I am not worried about lost data; I have the original logs, the data from which is in the database, and will feed them to Logstash manually, if necessary. The only thing I'll lose is time. But if the database gets corrupted every time there is a power failure and my only recourse is to delete the database and re-create it from scratch, that's simply not acceptable.