Rv Microwave I Am Trying To Find A Short In A 1990 National RV Dolphin And I Am Looking For Tips/products That Can Help?

I am trying to find a short in a 1990 National RV Dolphin and I am looking for tips/products that can help? - rv microwave

I have an electrical problem, which I think is a short in a National RV Dolphin 1990th I replaced the 3 batteries (x2 housing, starter x1) and saw all the batteries died after minimal use. Refrigerator, microwave, air conditioning and some lights did not work at all, even if the batteries are new.