You should have not powered up the monitor in the first place.
If the monitor was connected to the AC, the standby supply section would be active anyways, and thus damage may have been done from the beginning.
To have a chance for recovery, I would have taken the monitor completely apart, disconnect all the boards and modules, open all the shields, made sure that everything is very clean, and carefully dried as best as possible.
Then I would have let the individual boards stand out in the opened for at least several days, or bake them in a convection oven at about
95 to 105 degrees F. for at least 24 hours to dry them off.
After re-assembling, there would be a very good chance that the monitor will work again.
Because you put the power on while the circuit boards were wet, there is most likely damage. In consideration of the facts, I am very sure that you will have to replace the monitor.
--
As far as the child is conserned, I would find a proper way to deal
with him to avoid such damage in the future. I would seriously
consider consulting a child phsycologist to find out the proper way to
deal with this! In the future this type of behavour can lead to more
serious problems for you and your family.
Maybe denying the child from watching TV for a number of months,
limiting him to a very restricted social life with his friends, and
taking aways his favorite toys for the same period of time may
convince him to behave.
In the case of pouring a liquid substance in to an electrical device
there can be very serious safety concerns for electric shock and fire
hazard!
Jerry G.