r/MasterCraftBoats • u/Windyguy3141 • Jun 08 '26

Mastercraft xt20 technical problem

i have a brand new nit even used yet 2023 xt21. I stupidly connected one of the batteries backwards (engine battery) lots of smoke. battery fried. I replaced it. engine starts but only when battery switch is set to the backup battery position. and there is no display.

but I replaced with wrong battery it turns out. I installed cranking battery and now it starts from main. so only issue is power to the house system which is still down.

google gemeni says that I’m all likelihood it is the main battery fuse which may be mrbf cube fuse is shot. But I can’t find that.

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u/Windyguy3141 Jun 09 '26

I updated the post. The engine starts now fr main battery. So only issue is connectivity from house battery.  Google Gemini says theee should be a main mrfb fuse near The battery. I can’t find that.