How to unlock IBM Sony Trinitron monitor keylock?

[xygt]

Hi, first of all Happy Easter to all.

I have an IBM P275 21" monitor that I used the DAS software on to
adjust the brightness down with the G2 setting.
Once I removed the connector, I found that the keylock for the display
controls was enabled and I couldn't remove it. If I connected the DAS
connector again I could make display adjustments ok.

I believe there is a sequence to disable the keylock, but I can't find
it on Google.

Hoping someone may be able to shed some light so that I don't have to
throw away a perfectly usable monitor.

Thanks in advance.

Regards,
Xygt