Shark Shield flashing green light

I don't know what you mean by "sensors". When the unit is off, there's nothing you can touch on the outside that would give you a voltage reading. The fact that you're not getting a solid green light means you won't be able to check for the operating voltage either.

To check battery capacity, if you have model "C", it boots up telling you the percentage of the battery remaining. Fully charged battery will blink 10 times before another short burst of 3 green blinks. Half charge will blink 5 times before the short burst of 3 green blinks. There is no way to check for voltage on other models without opening the unit. To check for battery health, you really need to take the battery out and run capacity test using external equipment. You should look into the corrosion issue as well. That's the most common problem on SS. I guess you never read the article I referenced.

I guess you never read the article I referenced.

Excuse me, I've been busy. I'll get on that.