dbt85 thanks - new problem. My batteries didn't charge overnight, and now reports 0%.
There were some strange charge setting conflicts from App v Cloud and I turned both batteries off/on from their physical buttons, and managed to bring them back to life.
I've had the known issue when battery shows x%, then instantly discharges to 0% before. I think this was the case last night AND I think the new App has problems too (see other posts)
I think it's recovering now - a sunny day ahead to recharge!
Thanks for your interest