I had new U2 m. Did the update and the battery just dropped. Upgraded to 10.2 and it improved battery slightly but the wrist temp didn’t work. So I had it from Amazon and within the 30 days and I returned it. Since then I had a replacement and it’s been 48 hours and I’ve used 51% with cellular on etc. and I’m using 10.1.1. I did delete some of apps such as tops and depth and any that I would never use. Also some didn’t seem to work properly so that could have been an issue