I took my watch out my charger at 10 am and left on my desk without use I come back at 1:15 pm to check on it was at 79 % my brightness was at the lowest it can take. I tried everything to conserve battery. some days I get bad battery and some days good battery. If I put it in power reserve mode will this help conserve battery. The Apple Store says my battery is not defective.What can I do next ?