If you don't have power in the large black wire with the yellow trace when the ignition key is turned to start your problem is between the relay,ignition switch or fuse J.

Start by checking fuse J it's a 30 amp fuse in the fuse box under the bonnet, make sure it's not blown or missing. On the fuse cover is labelled as "F/L 30A IGN SW".

If this fuse is ok you will need to check if the large black wire with the yellow trace has power when ignition switch is turned to start at the back of the ignition switch.

No I don't think you have a problem with melted fuses they can be tight to remove. The 100 amp fuses are bolted in.