If you have a multimeter and a paperclip you can easily check the PSU yourself. The PSU have more than one kind of voltage to supply so even though you have juice supplying your fans from the molex connectors you could still have a faulty 3.3, 5 or 12V rail dedicated to your motherboard or even the SATA power connectors(drives won't start).
If you feel confident about it, unhook the PSU, take it out of the case and short one black(any black) and one solid green wire on the 24pin connector, using a bent-out paperclip(or something similar), that's the power-button signal. Then you can work your way down through the connector using the multimeter and check if you have voltages between any black(they're all ground) and a colored wire. If you have one or some of them not showing 3.3, 5 or 12V, chances are that your PSU is fried.
*edit* Just noticed that you're doing the Warranty-thingy lol.