I have a new out of the box nest e thermostat, four of them actually. I opened three boxes and one of them seems to charge via usb, say connect to port and then staying red flashing for over two hours and still just flashing red. The second one I tried won't even flash anything. Always nothing even charging via usb. Are these just bad units? I bought them from verizon.com and the boxes appeared new and sealed but maybe they are just so old the batteries are dead and won't charge?