Can anyone help please? I have a Hoover heat pump tumble dryer ATDHY10A2TKEX-80 which has developed a E21 code.

This happened after the water collector (in the door) overflowed. Only advise I can find online is about cleaning/drying out the condenser which of course it doesnt have in a traditional sense as its a heat pump model.

I have drained water out by turning the machine on its back but to no avail...