A2500 stuck in "loading" screen at charging station

My first A2500 lasted a week before a persistent error that customer service couldn't fix.

I got a replacement unit sent out five days ago. First few days, it mowed perfectly. Then two days ago, in the middle of mowing my front yard, it failed to return to the base station when its battery got low. By the time I noticed, the unit was unresponsive.

I carried it back to the base station to recharge, and despite good contact with the base station, it doesn't appear to be actually charging. While it has metal-to-metal contact with the base, it displays the loading screen (where it cycles around the perimeter of the LCD display) for about 15 seconds, then goes blank for about 5 seconds, then repeats. As soon as it loses metal-to-metal contact, it goes completely blank and is totally unresponsive.

I've tried resetting the unit by holding down the left and right buttons simultaneously, but even though it does the expected countdown, it never actually resets. I've tried powering up and powering down, verified the connections on the cord, verified a steady blue light on the base, inspected the underside of the robot, and deleted the robot in the app and tried to reinstall. Neither Bluetooth nor Wifi seem operational.

I don't think I'll be able to convince my wife to give this a third try, so if I can't get this fixed in the next day or two, I'm going to have to return this second unit and switch to a different brand.