That can happen if the BMC/ESM is bad, but if it updated ok, then it probably isn't that. It is probably the LCD itself. Does it blink if you hit the 'i'? Does it change to amber under an error condition (take the cover off, etc.)?
This one has me a little stumped. I received my Dell Poweredge 2850 today and while it works fine, the LCD on the front does not work. It originally came with the original firmwares and such. I've updated the BIOS to A07 and the BCM firmware to 1.83. I've also tried to reseat the connections to the LCD to no luck. The backlight seems fine but no text is displaying. I've tried cycling from none to default and then inputting custom strings in the BIOS but it still won't display anything. What else can I try to see if I can get the LCD working? I've included a video of what it's doing as well.   If it makes any difference, the server doesn't have IPMI or DRAC4 cards installed.
Dell Poweredge 2850 LCD Issues