DIAGNOSIS The machine is stuck in "Clean Alert" mode. This usually happens because the cleaning cycle wasn't completed properly, or the machine didn't detect that it ran.
FIX You need to manually force it through a recognized cleaning cycle. 1) Make sure the water tank is at least half full with fresh water. 2) Press and HOLD the "Clean" button for 5 full seconds until you hear a beep. The red light should start blinking, which means the cycle has started. 3) Let the entire cycle run. It takes about 15 minutes. You'll hear the water pumping and circulating. When it's done, it will beep several times and the red light will turn off completely. 4) Discard the first batch of ice after the cycle, as it will flush out any residual cleaning solution.
IF THAT DIDN'T WORK Try a full power reset. Unplug the machine, wait 2 minutes, then plug it back in. Immediately after it powers up, press and hold the "Clean" button again for 5 seconds to initiate the cycle as described above. This clears any temporary glitch in the memory.
HEADS UP The official GE cleaning packets are formulated to work with the machine's sensors. Using vinegar or other solutions might clean the machine, but it won't always satisfy the electronic reminder, which is why you sometimes need reset procedure.