car starts after second turn of ignition key

[bacillus]

I have an intermittent problem with my car. Sometimes when I turn on the ignition with the key the lights in the dash come on but nothing else happens.
if I turn off the ignition and try starting again the car starts normally with without hesitation.
I initially thought it was the battery at fault (was over 5 years old) so I changed that but the problem didn't go away.
Any ideas on what I should be looking at next?

[LC5F]

Have you replaced the head unit recently?

[bacillus]

Have you replaced the head unit recently?

I have a RNS 510 that I installed over 5 years ago.
Should also mention that vcds doesn't flag up any engine or central electric errors.

[GVK]

Ignition switch maybe going south

[LC5F]

Have you replaced the head unit recently?

I have a RNS 510 that I installed over 5 years ago.
Should also mention that vcds doesn't flag up any engine or central electric errors.

I asked as I had similar issue after replacing mine with an Android head.
Canbus didn't know what was going on and occasionally went into hibernation not giving power to ignition -an updated canbus unit was the ultimate fix for mine.
I found disconnect & re-connect battery would wake it up and it would re-set and whole car magically behaved as normal.

[bacillus]

today I swapped out the starter cut off relay that's located behind the cubby box and, fingers crossed, the car starts on first turn of the key. is this the cure, only time will tell...