2007 Fortuner instrument cluster problem. ECU issue ?

Hey glad to be on the forum. I came across the site as I was scouring the net looking for ways to rectify my issue.
I am posting in the 4runner sxn because I didn't see a Fortuner section. If this is not the appropriate place to post this topic I apologize and I understand if it gets removed.

Issue :
I have a 2007 Fortuner and around maybe a year ago I started experiencing issues with the lights and guages on the dashboard.
When I would start the car in the morning the lights and gauges on the dashboard would take about a minute to come on, flicker for a few seconds then remain on as normal. I let the problem go unchecked and it gradually got worse, over a year the lights would take longer and longer to come on and now a year later the lights don't come on at all until maybe an hour after driving. (I can still see the 'D' 'P' etc no problem but everything else is off,)

After going on youtube the common fix suggested was that I replace 4 100uf capacitors on the cluster itself.

https://www.youtube.com/watch?time_continue=350&v=3dQXdlUboLI&feature=emb_title

I am willing to try this fix but I have one concern. I noticed that when the lights on the dash are off, my reverse sensor and reverse (beeping) sound don't work either but function normally when the lights come on.

Would this suggest that the issue is not with the cluster but with the ECU ?

Other observations I've made are that during cold temperatures the lights don't come on at all. I live in a hot country so after about an hour of driving in the sun the lights and gauges eventually show but if it's raining they don't come on.

I'm at a loss for what the issue could be, hoping that someone here could point me in the right direction. I appreciate anyone who takes the time to give me feedback.

Thank you