Dell 5100CN alternating between Diagnosing & ready to print 093-424

Had a power issue a few weeks ago and still unable to get Dell5100CN to come back online.  Cleared a lot of errors dealing with toner cartridges (replaced 2 of them).  Now the screen is alternating between "Diagnosing" for about 5 seconds and "Ready to Print 093-424" for about a second. The 424 is replace magenta soon but even after taking all cartridges out and reseating - still cant get past this.  Printer is not recognized on network.  Thinking new board but looking for other ideas. 

Other pieces of info:

- Cannot get into menu for more than a brief half second or so (until it switches back to diagnosing)

- No Ping response

- Can hear a periodic 'clicking' 

- Everything heats up

- tried direct connect via USB - no success there but cannot say it is same issue.