Needing help with Defender (diesel) electrics. Its a long read sorry but tried to give all the info I could

Hello, hoping I can get some help with an electrical issue. I will try and explain what’s going on.
My neighbourr has a 2004 Land Rover 110 Defender (Aus delivery). She recently replaced all the park and indicator lights with LEDs. She also replaced the head lights with LED versions that came with a half ring LED DRL light. She asked me to wire these up for her, a simple task to meet our road laws regarding DRL’s. These DRL’s draw 0.2amp so I patched into the ignition line so they came on when the motor was running, ran them through a 5 pin relay on pin 87a (NC) that was switched by the park light positive that then switched the relay to pin 87 (NO) which interrupted the ignition wire feed to the DRL hence turning them off. (Our legal requirement here). Everything was working fine, all the lights worked and everything was fine.

The next day while I was cleaning up some other wiring I found from the previous owner, she mentioned that the cigarette lighter didn’t work and could I fit a USB point there instead. No problem, So while she was aligning her headlights, I removed the center facia, and started to remove the head unit to also fix the antenna lead that didn’t work. Thats when there were sparks when I pulled the unit out of it’s metal bracket, heard a couple of the fuses pop and the headlights went out.

Whoever had the car before my neighbour had used a double stack fuse plug to get and extra feed from the center fuse panel and had not properly protected the bare ends. I replaced the blown fuses (lights, radio, wipers) and a few others. Put a new connector and heat shrink on the feed line and then tried the headlights. Nothing. Tried the indicators, nothing, tried the wipers and ignition, nothing.
Checked the park lights and DRLS, they all work. The radio. Usb charger and hazard lights work (so the accessory circuit seems fine, but anything on the ignition circuit has failed.)

I grabbed the Muti meter and checked the ignition switch barrel at the end. There is constant power coming in, when you turn the key, the ignition line is active (but wipers, indicators, headlights, electric windows, heaters etc. all dead), the crank line becomes active but the engine does not crank. So the switch seems to be working and has not come apart as can happen.
I checked the contact points and the cables on the light stalk, wiper stalk and indicator stalk and ignition switch, checking each wire and all are becoming active when turned on but nothing is happening.
I have removed then checked every fuse in the lower center fuse panel and also under the drivers seat, again removing each one and testing them. I have looked at each relay and cannot see anything obvious (I have just found my relay tester so I will be checking them when I get some free time.)
I have looked behind the dash cluster as there are no ignition lights coming one, but the gauge lights all work. The indicator relay has been replaced with an LED version, the headline dim relay appears to have been swapped previously with a “bypass” 2 pin relay

So, until I removed the radio head unit and shorted out that live wire, everything worked fine, the car ran and all the lights and electrical equipment worked. After that, only the accessory side of things and the Headlight Flash work, but we are getting power to all the switches on the steering column and they are activating the feeds they are supposed to with 12volts, but the items they are connected to are not working.
So in conclusion, the items not working are, Headlights, indicators, wipers and washer, electric windows and any switch on the center facia, starter motor or engine.
What is working are the park lights, headlight flasher, radio, cigarette lighter (usb socket), interior fan speed, hazard lights
This coming weekend (As long as its not raining again), I will check the starter to see if it receiving power form the ignition starter cable (that is getting power when the key is turned to start). I have already checked the headlights and they are not receiving power even though the light switch is powering the cable when switch to headlights, and I will check the relays.
The battery is fully charged and the earth lead from the battery to chassis is in good condition and secure.

Is there a master really or something I a have missed checking somewhere. Not familiar with the land rovers (mainly work on Aussie cars), electrics are electrics, but we don’t have access to a service manual (yet) so am thinking there was something blown that won’t allow the power from the ignition /on feed to access the fuse circuit. Even though the switchings on the steering column are giving live feeds when turned on. How does the immobiliser in these car work, could that be the issue

Any help or advise would be greatly appreciated.

Thank you

John and Jaqui