Difficult to see how liquid would get in the head, short of being VERY messy with the processing chems, or a pipe leak in the ceiling above... A head gets
very hot so any liquid would not survive long. Condensation is ruled out by the fact you were using it for a hour beforehand. All very odd.
If you have a voltmeter, check the voltage at the lamp socket. If no volts when switched on, check the voltage coming out of the stabilizer. There may be an internal fuse inside the stabilizer which may be worth looking for if no volts coming out the stabilizer. Smell the stabilizer, burnt out transformer wiring usually has the distinctive sweet, sickly smell of burnt lacquer. Don't be worried by a small aroma: if it stings your nose or makes you feel sick, then worry
...
Good luck, Bob.