Edmund I guess you have it in DEMO-mode. Then it's supposed to go off after 30 sec.

Edmund If you zero it at some angle, it will show any new readings relative to you new 0-point. However, it will never show a negative number, only the deviation from your 0-point, but the arrow in FRONT of your reading will give you an indication. If it points down, it means your new reading is lower than your 0-point (i.e. a negative number), and if it points up it means a higher number.

Edmund The word LEVEL refers to the base, so a reading of 30.00 means that the measured plane is tilted 30 degrees from level (0 degrees). If you then push the ZERO button, the word LEVEL will disappear since it's base reading is now 30 degrees off level, and any readings will be relative to the new base. Push ZERO again, and it will revert to the calibrated 0 (LEVEL) baseline. The user manual does NOT mention that the word LEVEL will turn on or off like that, but it does.

Edmund Yes of course. :)

Edmund Powered by USB, type C port only.

Edmund Look at the close-up picture of the lock. The text under that picture tells you how to find the correct combination. (After all, it's not a high security device. :O) )

Edmund All the pictures show the same cane. The one that looks a little different is the one taken directly from the front of the eagle head. However... the head of the cane is just screwed on, so you can probably find another head the will fit.

Edmund The way it works is like this: You look at the "glass" from the same side as your phone or tablet is. You will then see the reflection in the glass, and you use that reflection to trace the image on to the paper that you have on the other side of the glass. Hope this made sense to you. :O)