Hello,
I have had a DS KV9102-1A door phone and a DS KH 8301-1A intercom for a long time.
Following your instructions, I managed to update the DS KH 8301. It became a DS KH 8301-WT.
I naively wanted to do the same thing with the DS KV9102-1A, but it did not work.
The firmware is V1.4.0 build...