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My first inclination would be to reattach keyboard ribbon cable.
I would also try to boot up with an external keyboard, that may work - check your hardware in device manager.
Are you sure it is the keyboard only that is dead at this point or is there the possibility of another part not working also? Might do a complete disassembly/reassembly to make sure you didn't miss a connection.
An external keyboard works, and check the ribbons are connected OK, no conflicts in device manager, both keyboards showing OK
however when the internal keyboard is connected the touchpad disable switch doesn't turn off, but when the internal keyboard is removed the touchpad does enable and disable just fine