That is the timer override button. Did you try plugging in and charging while the blue light was on?
If not, it didn’t prove anything.
If yes, and it wouldn’t charge, the problem is something else.
Do you have a multimeter and some basic electrical knowledge?
1st Capacity Bar loss 30k mi 16.25mo
2nd- 49k mi 25.5mo 51.5Ah
3rd- 73k mi 36.5mo 46.9Ah
4th- 86.5k mi 43mo 42.61Ah
5th- 101k mi 50.5mo 38.38Ah, end 36.13Ah
New Battery 9/28/15 104k mi 66.14Ah
1st- 160.5k mi 34mo 54.02Ah