I’d check the thermostat band to see if it’s rusty, and the probes around the right way and connected properly (problem1) then if the steam boiler was emptied the pump will run for a long time to fill it back up (problem2)
Other than this we start running into split boiler seams when hot causing loss of steam inside the machine, not coming to temperature and blowing the Triac board.
From memory 23 is communications error and high counts are usual, 21 is a little different, maybe probes but I’m guessing, I’d seriously have to go into work to check that one.
Hope this helps.
Duane