I use B to cycle POW and Swr to make ture things are working properly.?
Blinking power symbol is correct for full power on internal battery. On 13.8v there will be no power logo.
One other thing you can do is calibrate the battery voltage display. This is an internal menu item, but I found that mine would show a much lower voltage than the battery had available. I don't think the display has anything to do with when the transmitter will reduce power, however.?
Tobias KK7BCO/2M0TFF