Chosen Solution
Yesterday i had my battery replaced because the old one was bad. I came home and put it on charger to charge it fully since it was dead. After several hours it was 100% so i unplugged it. I was just reading something online when it suddenly shut down. I tried starting it and nothing showed. After plugging it back it showed that the battery was drained and it started and showed about 11% battery. I charged it to about 75% unplugged it and started messing around in settings when it went off again. After few of theese i noticed that the battery dies when it should lose 1%. For example it was 75% and rather than going down to 74% it lost all of its battery. I had the battery changed at service and not at apple store because there isnt any near to me.
It sounds like you have a defective battery. Or at the very least, a used battery that has damaged cells. Take it back to the service and report the problem, they should replace it at no charge. Defects happen, so unless this is a common occurrence with the service you used, it may be totally random that this happened.
