faulty a500 testing...

[Azryl]

Um.. how about you try booting the machine without the keyboard connected?

Anyway... all Amiga's should boot without a keyboard or when the keyboard is faulty. The first thing to try is to swap the CIA chips. They both control different sides of the Amiga peripherals and some internal timing.

By swapping the CIA's first you might get a different boot problem.
IF you get further into the boot sequence then begin to swap chips. It is very unusual to burn out something on the motherboard unless you have inserted parallel/serial/mouse cables while the machine is powered on.

This is a good way to fry CIA's and sometimes the logic on that port, resister or diodes etc

Az

[Azryl]

Paula and the CIA's do all the glue logic for the floppy drive and DMA sections to the memory bus. So your incorrectly inserted floppy header most likely did damage to Paula, Odd and Even CIA and probably Gary as well.

So you will need to buy/find/steal some extra CIA's so you can check Odd and Even with new reliable known working chips. Then Paula, lastly swap  Gary.

If the mobo still fails to boot....  buy an A3000

Az

[Azryl]

Oh, there is the possibility that the miss-aligned power pins ( 12v + 5v ) did damage to some of the resisters/diodes at the Floppy port....  not sure of the procedure to check these.

Hope someone with more hardware knowledge gives a hint!

Az