Are you sure it was 25V not 25W? It makes more sense to be 25 Watts since that's around the operating wattage that the Slingbox uses. You can figure out the actually wattage by multiplying the "Volts" by the "Amp" and that's the possible wattage output.
As for the Slingbox, there's a label on the bottom of it that indicates the proper power input requirements. You'll see a label that indicates the Volts, Amps, and Polarity requirements. You should be able to compare this with the specifications on the AC power adapter to ensure you are using the correct one. However, if the power supply malfunctioned and overloaded the Slingbox, you probably will need to have them both replaced.