Power issue with second battery

[zjKrawler]

Having a problem with new set up. Just installed 2 XS Power 3100 amp batteries running in parallel. Wired positive to positive and negative to negative, the main is still wired accordingly to factory grounded to block the second I’ve grounded to the chassis in the rear (96’ zj so it’s unibody). My issue is I get no output from my amps other than odd engine noise. Basically sounds as a mic was hooked up in the exhaust. Before the change all worked great and was getting 140’s. Set up includes 4 SKAR EVL 12D4’S, 1 SKAR RP 3500.1D pushing 2 and 2 SKAR RP 2000.1D one each to the other 2. I have a split chamber box one chamber for 2 shared subs. Running one inverted per chamber. Upgrade included the batteries more power cable upgrading to a dual 1/0 power and ground per amp. Big three upgrade with 2/0 ga as well as silver plated terminals for speaker input and 200 amp gold plated fuses per power input line. Have a 250 amp coming off main and a 250 amp before aux in back both fuses approx 12’’ from connection. As mentioned batteries are wired direct in parallel and grounded separately. I’ve read some wire second bat direct to main bat ground on block as well. Nothing else has changed except I get zero output now from head unit it seems and instant feedback through subs when started. Ran a test on new box a few days prior and all went great sitting in the high 130s on 2 12s with the redone port at 52 sq in tuned to 32 so that’s a massive improvement. Any ideas out there? This is my first time going this deep into the power end and never had good returns when adding second batteries. Solved my box issue by building braces from 1/4 flat steal bar stock and 1/2 bar stock creating I beams only using up 8 cu in total per chamber and left extremely strong.