This is your best shot:
Dismantle and remove from the case, wash it in clean warm water and scrub with an old toothbrush to clean the soldered side of the pcb. Now, carefully scrub around the component side, paying particular attention to cleaning between the legs of the components themselves and be quite thorough about this. Wash the set in running warm water from the tap and immediately immerse it if methylated spirit to remove the water. Shake out the meths from the set and gently warm and dry it with a heat gun till the board feels warm then leave it in a warm dry place for a few hours.
If that doesn't cure it and bring it back........ it's knackered!!
The secret to resurrecting immersed sets is to immediately remove the power, keep the set immersed in fresh water till you get home and immediately carry out the above procedure. If the set has been allowed to stand around and dry out, there's a good chance you will lose it since oxides and other conductive deposits form on the pcb and on the plastic component bodies These deposits will conduct between the component legs. It is very important to use the methylated spirit wash cycle as this removes the water after washing and prevents conductive films forming during the drying process.
The circuits most affected by these conductive deposits are the Rf (radio frequency) sections of the set and these will die immediately as they are particularly sensitive.
Remember too, that when drying out the set, although the board and components may appear dry, the small coils which are enclosed in small metal cans may actually still hold some water so leaving it to dry out in the warm for a few hours is important.
