Keyboard and mouse not detected

Did you re-connect the keyboard?

can you plug in a ps2 keyboard?

sometimes usb keyboards arent detected by the bios. you may need to plug in a ps2 keyboard and then enable the usb keyboard option in the bios

Check your PSU and 5V Standby. That is use to power the USB and other logic to enable the pc to boot.

Disconnect other USB device on your pc. BAD usb devices my load up the 5V Standby and will prevent USB keyboard and Mice to function.

"system fan has failed" there's your clue.

One of the fans in the pc/server has failed and the bios has detected this and pops up a message during post for your information.

The reason you can't do press a key, is probably your KVM is USB and the ports haven't been initialised, thus they aren't detected.

You will need to replace the faulty fan or disable detection in bios as temp fix.

i thouhght he said he replaced the fan?