Existing touch screen display was fully functional but faded, apart from this the microwave was working as it should
I ordered a replacement screen AP3182993 and fitted it, making sure the ribbon cables were secure and correctly fitted.

When powered up the microwave started to 'bleep' repeatedly.
The display would change from the normal cooking menu to displaying a message 'Call for Service' in time with the series of bleeps.
If the bleeps are a code in numbers it could be 3,2,2,4,4,2,4. It was difficult to tell as it was rapid. It could have been just bleeping.

Using the touch screen display all the clock could be set and I was able to select a program for cooking and start the microwave.
But the microwave would then start and stop in time with the message.

I then removed the new touch screen display and replaced the original.
The microwave worked perfectly with no errors flashing, bleeping etc.
Of course the display was still faded!

The new display uses more modern components (SMDs) but otherwise is identical, the same ribbon cable & other wiring and the display menu is identical too.

Any suggestions?