Regression verification

Hello good people of the internet.

I was wandering if someone could help me to validate if my data is in control or not?

The data consist of a current output, used by a motor to open and close a lid 1000 times in total (1000 cycles).
every time the lid opens and closes once I want to observe the current of one specific point (this means that I get a total of 1000 points).

When I plot those points (current on y-axis and cycle nr. on x-axis) and make a regression through, I want to get a straight horizontal line.
We all know that this line wont be exactly straight. So I want to be able to validate if it is tilting too much or not.

I think the one way to validate it, is to look at "\hat{b} / error < 2". I have found the error with excel using "data analysis -> regression", but I don't know how to find \hat{b}. I also dont know if there is a better way to do it?

If you can help me I would be very thankful.

Kind regards.