Mavericks keyboard problem

My friendinstalled 10.9.2 on the macbook 2009. Unfortunately after the installation, the internal keyboard stopped responding (typing only spaces or nothing at all and three characters on the icelandic keyboard he has), but works well with the usb and bluetooth keyboard. I tried to reset the SMC and NVRAM but the niether keyboard is taking the commands, it does not even go into the safeboot mode. I can only use the boot commands for verbose or recovery mode. I have not found any clues for this strange behaviour. What could I do to get the internal keyboard again? Should I downgrade back to 10.8... (which is going to be difficult since he has not kept any backups of his old installation)..??