DIAGNOSIS The machine is stuck in its initial setup or post-descale mode. It's waiting for you to confirm the priming is complete, but the touchscreen can be a bit finicky.
FIX You need to press the 'Confirm' button on the screen, but it often requires a very deliberate, firm press right on the center of the word. Don't just tap it. Press and hold for a full second. You should hear a beep and the message will clear, letting you brew.
IF THAT DIDN'T WORK Unplug the machine for a full 60 seconds. Plug it back in. It will likely go through the 'HELLO' sequence and then show 'Prime Line' again. This time, press 'Confirm' immediately after the screen fully illuminates.
HEADS UP This 'Prime Line' lockout happens after every descaling cycle too, not just first setup. It's the machine's way of making sure the internal lines are full, so you'll have to go through this press-confirm dance each time.