So brand new to jetskis. Have turned a wrench a few times on cars but wanted to give it a go. I picked up a 1996 Seadoo gtx. Was told it just needs a new solenoid as he jumped the solenoid and it ran. After putting a new one in it turned over and over but couldn’t get it to start then sparks came from the negative terminal and now nothing. It sounds like there is supposed to be a second ground coming off of the battery however there isn’t one and on some further research it looks like a 1997 rear electric box was swapped in. Any advice on how or where to start trouble shooting?