How to re-calibrate a Husky 9 digital level.

Can anyone tell me how to re-calibrate a Husky 9 digital level? There is a combination of button or buttons that you need to press to re-calibrate it. It is not in their manual. So I called Home Depot/ Husky at 866-513-6723 and asked to speak to their tech support. Customer service told me to tell her what the problem was. She looked it up in her computer which probably has the same manual as I do and told me there wasnt any way to re-calibrate it. I told her there was and insisted on speaking to tech support. She asked for my name, telephone number and e-mail address and said she would ask the technicians if there was a way and get back to me. So I asked her why I couldnt speak to the technicians myself. She said the technicians were in China.
How do I know there is a button combination to re-calibrate it? I made the mistake of letting someone play with it which is when it lost its calibration, and no this person did not drop it or hit it because I was there and would have seen it, and yes it was working perfectly fine before and no its not the battery.
There is number on the level which I assume is the model number: G7041798.
We all better learn to speak Chinese as soon as possible or else were never going to get anything done.
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