I have a Dell Optiplex that runs a small CNC machine. The other day I started the computer and while it was booting up I turned the key board over and tapped it on the counter to remove some metal chips that were stuck in the keys. The computer quit working. I opened the back and saw a green blinking light on the mother board. I was told to replace the power supply. I did. Now I have the green blinking light on the mother board and a blinking amber light in the start button and nothing working on the computer. I don't know what to do next.