Hello, I took my MBP 2010 17" to an Apple Store due to possible issue with a trackpad (automatic clicking after upgrading to Sierra). The staff did a test on my computer and found that the battery failed the test. I think the result showed that the batter is losing its ability to hold charges (about 75% ok). He mentioned that as it is an old machine, even there is a hardware failure, Apple cannot do anything due to a lack of components. Also, I seldom used the computer for about four years as schools bought me more recent rMBP. Despite the result, every time I charge my computer, I get 100% full showing up on the top right of the screen. Do I have to worry it for the time being? Will the machine fails to function if its ability to hold charges drops to 50% or below? How long do you think the computer will last?