Is that 'leaked' area wet? If not, it isn't leakage, it is simply an adhesive they add to hold the parts. I can't find any info on that unit online.
Unless someone else has a different idea.... Can you get at the bottom of the board and take a picture? Trying to determine the lead outs of the amplifiers on the heat sink. How are your soldering skills? I think we will need to remove all three of the amplifier chips and then see if the power supply comes up. If it does, we can replace the amplifiers one at a time to try and figure out which one(s) are bad. Then we would need to figure out a replacement part.