Tektronix 11401 dsy kernel failure

[Johnny10]

I just purchased a Tektronix 11401 Oscilloscope with 2- 11A52 Plug-ins.
On start-up Self Test Error "dsy kernel failure" Second Line  "Exec Communication" is displayed on screen.

Since Kernel Diagnostics failed the Self-Tests will not run.

I have a copy of the 11401/11402 Service Reference
But I haven't found the meaning of this error other than the problem is on the A7 Display Controller Board since red LED is lit.

Anyone familiar with this issue?
Voltage on board is within limits.
Lithium batteries are 3.1 volts