[need help installing 370 amp mechman alt in my 2015 yukon]

im new to this forum and im looking for some help for my install

has anyone ever installed a mechman alt on a 2015 or newer yukon denali?

i put 1 in already and it went bad(loud humming noise) in about a week.

so i sent it out and mechman fixed it but the rep said i had it grounded wrong?

he said you ground the newer style trucks different???

right now i have 1 yellow top optima battery up front

luckily there was a empty spot for it and i still have the factory battery

i ran 0 gauge from the positive on the factory battery to the yellow top

then i grounded the optima battery to the frame

then i ran 0 gauge from the alt positive to factory battery and grounded the alt

to the factory battery with 0 gauge also

what am i doing wrong ???

i couldnt understand what the rep was saying about the grounding issue!

sorry if so confusing i tryd to explain it the best i can....

also would like to know how many batterys would someone run for my system?

looking to use xs batterys in the back .should i take out the factory batterys and yellow top optima?

if you think i should add somthing or somthing is wrong with my set up im all ears!!

pics coming soon!

i have.....

4 1000/1 slash v2 jl audio amps

2 600/6 jl audio amps

4 13.5 w7 jl audios

6 6*9 jl audios

4 6.5 jl audios

1 audio control LCQ-1 sound processor

factory head unit