Precision 7710 (2017 build) won't turn on - constant flashing battery LED and power switch LED

I have a Precision 7710 not powering on with both power switch LED and battery LED constantly flashing white. Pressing power button makes both LEDs stop flashing and machine does not come on. Changing battery and power brick with another model, (7720), both batteries, and bricks, work fine with the 7720, with 99% battery showing. The 7710 had been on and being used with Windows 7 and just shut down with no warning windows or messages. CMOS battery checks good with 3.02 VDC.