Pure distilled water does not conduct electricity - put some sugar, tea and milk into it and then it does conduct electricity - regular tap or bottled water is a conductor.
The liquid will have joined bits of the circuitry together - some may have dried out leaving difficult to see conductive residue - some may not have dried out - some electronic components may have been damaged.
There may or may not be a fuse on the back of the radio - the water may or may not have caused a fuse to blow - fuses are easy to check & replace. It's more difficult to remove the liquid contamination - imagine pouring a cup of coffee onto your computer keyboard - a long repair job.
Sometimes a garage might have to wait for the dashboard specialist to pay his regular visit - of course - you could always ask your "why so long" question of the garage.
Good luck...
Peccavi
June 2013