Xantrex 458 freedom issues

[96vectra]

Curious if someone has had this issue with the xantrex 458.....
Today I go to u winterize my rv. I knew the batteries needed replaced last year. (All worked flawless last season).
So I get 2 new coach batteries and start hook up of inverter/charger...
Positive first..then try neg cable. Well, sparked like crazy. I figured just heavy load. Well I tested with multi meter and neg cable from inverter has 12 v .... that's not normal. And when I try and plug into to shore power it now trips my gfci outlet that has always worked in post for rv.
Generator runs and seems ok other than no charge due to I'm not hooking up a hot neg cable..... so now ofcorse after putting away for winter with all working.... i now have an inverter that doesn't work and can't plug into a/c. Question is.... is the inverter a fluke deal and is something wrong with my transfer switch? Or is my inverter junk?
Any ideas helpfull.

[deandec]

The negative or positive cable from inverter should not have a voltage if you have disconnected the shore power and stopped the generator before doing your wiring from the battery to the inverter.

It does sound like what you view as the negative, inverter to battery, cable may be connected to the positive terminal of the inverter.

[96vectra]

I didn't notice the a/c plug tripping until after. And only the positive cable is hooked up from inverter to batts. I have neg cable taped up because it's hot. There are only two cables. Red and black. Strange thing is....i unhooked old batts and install new . Everything worked perfect last year. I even unhooked checked power terminals at inverter . Same deal. 12 v on both posts.