

You should be able to play a video that’s at 100% even if the torrent isn’t complete.
It could be a codec issue? If you’re using windows there’s a tool called MediaInfo you can install that’ll analyze a video file and tell you if it’s corrupt and what codecs it uses. You might just need to install a codec pack like K-Lite if your system doesn’t already have the codec you need. Or, like an other commenter said, try opening it in VLC which has killer codec support built in.
This happened to me once and I completely overthought it.
In my case, I removed the PCB from the drive and took a close look and saw a single scorched IC that I figured was the problem. I think it was a voltage regulator or something like that.
So I bought a scrap drive and tried to transplant the PCB onto my dead drive, but of course that wouldn’t be able to read my old data.
So took it into a local electronics repair shop and asked if he’d be able to make it work.
He took one look at the damaged PCB, pushed the scrap one back at me and said “yeah I’ll just replace this part.”
40 bucks later I had a working drive again and was able to rescue the data.