Should I fit my parameters with brute force
If you don't know which of the 10,000 sensors are good and which are bad, the data from those 10,000 sensors is useless for training a regression line / classifier.  You need labelled data, where you know both the value of the features and the health of the sensor.

Moreover, to be effective, you probably need your training set to contain both healthy sensors and bad sensors (where you know which ones are healthy and which ones are bad); it's not enough to just have data from bad sensors, because that doesn't tell you what healthy sensors look like.  In a pinch you could use one-class classification, but I don't recommend it -- your results will probably be poor, and you'll probably be better off obtaining labelled data from both healthy sensors and bad sensors.