Glad to hear the issue is resolved and I appreciate the heads up.
If my answer was helpful, please click: KudosForum Member since 2001I am not employed by Dell
This worked for me also. Thanks!
I had a client with this exact model of Optiplex and the identical POST codes (1, 3 and 4) plus the blue power button. The steps worked perfectly. Thanks for taking the time to document this!