2003 Predator 500 sparking when ground is connected

Hello, I am new to the forum. Lots of experts on this forum! I have had my 2003 Predator 500 for about 5 years w/o any problems besides the regular maintenance. Last year I had a cheap Batteries Plus brand battery that left me stranded twice on the trail. I replaced it with a YUASA YTX9-BS battery from the Polaris dealer, but after I connected the positive and then tried to connect the negative, it started sparking and melting the ground terminal. I thought I may have overcharged it, so I bought another battery, but had the same results. I don’t think it is anything major because it was working fine with the cheap battery, besides not starting after a long ride. Not sure if it may be a starter/solenoid issue? Thanks for any advice you can give me.