Neptune stops after approximately 5 seconds

Hello,

I've seen similar questions posted to my exact problem, however I am unsure which part I should try first.

The washer will operate for about 5 seconds, the will turn off. I've followed the service manual diagnostics:

Removed the J4 connector and performed the motor test; Motor operates at tumble speed
Inspected the RD30 (red) wire and looks fine. See no obvious burn marks on the circuit boards.
Have removed main board connectors/plugs and re-inserted in order to wipe the contacts.
Have removed timer connectors/plugs and re-inserted in order to wipe the contacts.
No sign of corrosion.

So, seems like a problem with either the timer or the main board. This did happen all of a sudden, and the prior wash cycle went to completion.

Any advice as to which to replace first, the Timer or the Main Board?

As an aside, the motor / control board and wax motor we replaced about 3 years ago. Also have replaced the bearings. The timer was replaced about 10 years ago.

Thank you for any pointers.