You ever make it over to Columbus Car Audio on Morse Rd?I highly doubt the OP is coming back.
That said, he never said he installed a capacitor, rather, one inside the amp blew after he hooked it up and powered it on 10 seconds later.
I’d chalk it up to an electronic item failing as they sometimes do, perhaps a manufacturing defect / shouldn't have passed QC, add cheaply made quality to it which doesn’t help, or something we may never know since we weren’t there to inspect the wiring.
Even hypothetically, if he had an external capacitor installed, that would not blow up based on powering the amp up. No amperage difference, none of that. You will see sparks if you charge or discharge one without a resistor, but very unlikely to blow one up unless wiring it backwards. Tons of people charged them by pulsing the power cables to the battery or just installing a fuse, not the proper way to do it and I do not recommend that at all, but never seen any failures.
At any rate, I agree with those that said it was likely a dud from the factory, a random failure, or old and the caps were past their life span. If it's a new amp, of course just warranty it.