I'm assuming as well that the keyboard itself is borked, but one final thing you can test is to load into the BIOS and see if there's a place you can type (stay away from the Password section, in case you enter an untypeable password), basically just to try and bypass the operating system. Alternatively, if the computer is old enough, boot into DOS and try the keyboard there, or a bootable Linux CD or something.

But yeah, it's probably dead. It is interesting that the ASCII codes are 78 and 87, but unlikely since once you convert them into binary they're 01001110 and 01010111, so they're more than a couple flipped bits.

I work here