[Elecraft] K1 problem during Alignment and Test Part 1

[dawgpile at roadrunner.com]

Thanks in advance for any advice...

Symptom:
Without filter board installed, unit powers up and passes LED tests. Absolutely nothing appears at any time on the LCD display.  I thought I might be having a display problem until for giggles and grins, I popped in the filter board and powered up.  With filter board in, LEDs behave as expected, relays can be heards twiddling, and then the E42 error code is displayed for a short time and then the display goes blank again.

In either case, with the display blank, subsequently pressing any of the buttons produces nothing.

Other things I've done... I've looked at every pin of the display with a scope to verify no shorted pins.  Likewise, I've looked at every pin of the PIC on the FP board with a scope to verify no unexpected shorts to gnd or Vdd.  Can see activity on the SDA and SCL lines as well.  Checked U4 for proper voltage out.  I've physically inspected every connection to check for improper soldering.  (I'm a very experienced kit builder and can honestly say I've not had a problem with improper soldering.  I've missed the occasional pin though ;-)  Physically inspected RF board as well.  Voltages good.  Solder joints all seem good and present!

The PIC on the FP board is definitely running, and because the E42 error code displays, albeit temporarily, I know the display is good.

Why no E27 code at all?  Why doesn't E42 code stay, so that a tap of a button gets me to the next state?  Again, thanks for your consideration,

Kelly NN8E