Please check the terminals of the battery as you may have them reversed.
This is what I always mentally do when connecting batteries.
Find the word "NEG" or the symbol "-" marked on the 12VDC batter case. Make sure this battery cable goes to the frame ground connection that should be very close to the battery.
If it has been connected in REVERSE POLARITY you need to find two fuses in the 12VDc POWER DISTRIBUTION PANEL that is marked "REVERSE POLARITY" There may also be an IN-LINE fuse very close to the battery terminals as well.. First be sure the cables are on the correct terminals of the battery and then replace the blown fuses described above...
Let us know what you find out...
Once you get it hooked up correctly I would use some RED fingernail polish and and mark the POSITIVE cables near the battery terminal.
It is confusing to go by the color of battery cables as if RED and BLACK colors are used the BLACK goes to the negative terminal and the RED goes to the positive terminal. If WHITE and BLACK color cables are used then WHITE goes to the negative terminal and the BLACK goes to the positive terminal. Any added fuse blocks etc usually all go to the marked positive terminal..
ALot of us have crossed the terminals as it is so easy to do. One thing that happens is the manf of the same battery will relocate the terminals on their battery to the other side and of course you will most likely hook up like the battery was positioned before. Just takes one little spark to blow the fuses...
Roy Ken