97 wrangler redoing system melted power lead

Helping a friend with repairing his system

97 wrangler
4L 6cyl 5 SPD

JVC CD player with USB and 3.5mm input

Amps
JL g4500
Kicker monoblock 500.1 zx/ series or kx I thjnk

Stereo speakers
4 After markert coax

Sub
Sound stream t4 12in dvc 1ohm stable

My buddy melted his power wires from the battery to the amps
Due to what I'll guess is using too small and cheap powerwire (10 gauge) when he needed to running quality 4awg

Since the power wires were melted all the way from battery to the amps should the grounds and remote turn on wires be replaced also
And do the amps need to have a volt meter check the input and out puts is there any visual inspection needed on the amps boards etc ? Before it has juice put to it?

Also
He had the dvc sub wired in parallel to the monoblock , which would of been running that kicker mono amp way below its approved ohm load srability which I'm sure didn't help

He bought quality 4awg and a new inline maxi blade fuse holder
A distribution block 4awg-8awg
I'm trying to help him reinstall its done correctly etc. As I don't know who did it originally

Will a quality 8 gauge wire be suffcient? Or is 4 gauge a must for the power leads off the distribution block
And
What should the nax length of the power wires be.? That come off the distribution block to the 2,amps

For grounding is 4 gauge necessary or is 8gauge sufficient I know they need to be less than a foot long

Grounding should not be to floor board correct? Where is a good alternative grounding point


Since its in a wrangler and he likes having the top removed,offroading etc. I was going to put 1/2 inch spacers between the amp and floorboard, to help minimize the amps direct contact with liquid on the floor board considered mounting them upside down and also using the spacers between the bottom of the amp and seat

The sub enclosure is also being redone due to water exposure it calls for a 2.2 cu ft ported which he I think had behind or under the back seat

I'm also shrink tubing all convections and then wrapping them in high grade electrical tape for weather proofing

Thanks

DO not mount the amps upside down! Do read the what is a proper ground sticky and the Big 3 sticky.

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