Pentair Warrior SI isn't receiving power

Issue:
My Pentair Warrior SI does not appear to receive power from the power supply/control unit. The power supply/control unit works correctly (the lights turn on, there's no detectable light flickering, the buttons work as they should, etc.), but the blue LED indicator on the front of the robot doesn't come on. The robot does not move nor does it make a sound or indicate it's struggling to turn on in any way. I plan to take it to a local pool store I trust, but before I do that, I'm trying to gauge whether this might be a quick and cheap fix or if I might need to replace the entire unit.

Other important information:

• The communications cable running from the power supply/control unit to the robot is undamaged. I also unplugged the communications cable from the power supply unit, cleaned it, and plugged it back in. The prongs were already clean and uncorroded.
• I removed the motor unit and separated the housing to make sure there wasn't any water trapped inside. Based on what I could tell, I couldn't find evidence of water having gotten inside the housing before. All of the circuitry appeared clean and undamaged. All wires appeared to be seated correctly.
• I tried plugging the pool robot into different outlets outside (and one inside on a different circuit). The issue remained the same.
• Admittedly, I left the robot in the pool over the winter and had not turned the unit on for a couple of months. In terms of water treatment over that time, I've only been in the habit of adding chlorine. This robot issue + the summer starting is a clear reminder to get my act together when it comes to robot care, appropriate water and pool maintenance, etc.