LDH 4 HZ showing on dash

Perfect day to stretch GRiSO's legs yesterday, noticed a bit of a drawn out start when firing up.

Got back and decided to check and clean battery terminal and connectors, that done, turned ignition on and the dash displayed the service icon and LDH 4HZ, wtf? started ok, but with a blank dash?, rechecked connections and fuses, all ok. Pulled main 30amp fuses , put back in, no change .

Light bulb moment , pulled the main 30amp fuse again and waited for a few minutes this time. Put back in, ignition on and all back to normal  sweep and operation again. Phew!!

Couldn't find what LDH 4HZ and service icon indicated.
Did this come up through jiggling the battery connections and having an intermittent power feed?
Any clues??

It's the identification boot code for that model of dash. Once it has been powered down by being disconnected, (Or if the ECU just shuts everything down due to low battery voltage detection.) when power comes back on and it re-boots you get the message. It's not a fault code or anything, just ignore it.