DIAGNOSIS The main control board has likely locked up or detected a fault. It's essentially having a full-system panic attack.
FIX Perform a hard reset. Unplug the washer from the wall outlet. Not just turning it off at a switch, but physically removing the plug. Wait at least five full minutes. This drains any residual power from the control board's capacitors. Then plug it firmly back into the wall. This often clears the error and the flashing lights should stop, returning control.
IF THAT DIDN'T WORK There could be a wiring short or a failed component, like the user interface panel or the main control board itself. Check for any obvious signs of moisture behind the control panel or chewed wires if you have pests. But if the hard reset does nothing, it's probably a board-level failure.
HEADS UP Don't just keep plugging and unplugging quickly. The wait time is crucial to let the electronics fully discharge. If the problem keeps recurring after a reset, the control board is likely failing intermittently and will need to be replaced.