Second GPU is lost (nvidia-smi) after seconds/minutes in Ubuntu

I did not, thanks for your suggestion. However, when I tried to load the GPU again today, it was totally fine. My best guess is that the unstable power delivery (due to the loose cable) made the entire device unstable. I think that the fact that the power cable was plugged in properly, and the fact that it sat idle for a couple of days, restabilized it.

Thanks for your help anyway!