There are other similar threads about so you need to check those.
Did you use a pressure washer? Did you wrap up the "delicate" parts with polythene before you started? I will assume the worst but even with precautions the cause may still be one of these below.
Some initial ideas are as follows:-
Water in the spark plug holes.
Water in/on the HT leads.
Connection accidentally dislocated.
Check all connections. Use absorbent towel to remove any extraneous liquid from anywhere it should not be. Use WD40 (or similar) liberally over the entire HT system, in fact use it everywhere because not only is it used to dispel water it is also recommended as a cleaning agent. Double benefit.