It would not be possible to be definitive about the fault with your Kwaker LCD, but here are a few general points.
(1) The problem could be with the LCD display itself or with the signal feeding the LCD.
(2) LCDs can just fail outright and need to be replaced, but they normally degrade so the there is still an image but the display would be missing parts or be dull.
(3) Presumably the LCD is reflective, rather than back-lit (transsmisive) so a faulty back-light would not be the problem.
(4) A common problem with LCDs is the connection to the LCD display itself which can become miss-aligned.
(5) In general, on a motor bike especially, connectors can become loose, wires and connectors can corrode, and wires can even fracture.
(6) Moisture ingress will render an LCD completely inoperable, but in most cases once the moisture has dried out the LCD recovers.
But at the end of the day, you will probably have get a specialist to have a look at the problem.
spec
PS: just a thought, as you are from Sweden, has the bike been exposed to extremely low temperatures? Low temperatures (and high temperatures) can make an LCD permanently inoperable.
Its been some low temperatures, near zero degrees celsius, but the instrument broke down while the motorcycle was stored in the shed. The only thing that I´d done was connect a battery charger.
There is some simple tests in the workshop manual, and the first one fails.
I connect to 1 and 3 first, and when connecting 1 to 2, the back light turns on, but none of the segments.
Its been some low temperatures, near zero degrees celsius, but the instrument broke down while the motorcycle was stored in the shed. The only thing that I´d done was connect a battery charger.
There is some simple tests in the workshop manual, and the first one fails.
I connect to 1 and 3 first, and when connecting 1 to 2, the back light turns on, but none of the segments.
Hmm, so the LCD is trans missive, with a back-light.
As the back-light is not coming on, in normal operation, it would indicate a fault not connected directly with the LCD.
Has the bike got damp?
Is there any chance that the battery charger has applied too higher voltage.
Is the battery on the bike OK?
Check for corroded connections, especially earth connection to the bike frame. Also check the battery terminals for corrosion. Sometimes there is a battery connection with heavy cables for the starter motor and thinner wires for the bike electronics.
Hmm, so the LCD is trans missive, with a back-light.
As the back-light is not coming on, in normal operation, it would indicate a fault not connected directly with the LCD.
Correction: Back light is coming on, but no clusters are lit.
Has the bike got damp?
-- No visible damp in instrument, shed seems to be pretty dry.
Is there any chance that the battery charger has applied to higher voltage.
-- That was my initial thought, but I´ve checked the specs for the CTEK charger and it looks to be OK for the battery.
Is the battery on the bike OK?
-- Yes.
Check for corroded connections, especially earth connection to the bike frame. Also check the battery terminals for corrosion. Sometimes there is a battery connection with heavy cables for the starter motor and thinner wires for the bike electronics.
-- I´ve tested the instrument on my workbench, using a 12v supply, so no bad connections to blame for this.
I got it working last october, I took it off the bike and on to my work bench and took it apart. Did some tests as explained in the Kawasaki manual and suddenly it started to work.
But, now, almost a year later it fails again, and it didn´t make any difference to take it apart. Probably dead this time, need to find a replacement...