If you post a schematic of what you have there are several people on here that have a lot of experience with mosfets and they may be able to help you. I can tell you a few things from my experience. If the mosfets are getting real hot and then dieing it is probably because they are not being turned on all the way. If you are not using mosfet gate drivers that would be a good place to start. If they are just suddenly dieing then you may be zapping the gate with spikes and need some protection like a zener from the gate to ground.

I have not used SSRs so I really can't comment about them. I have used SCRs and they will not work for what you want to do I don't think. Once a SCR is turned on it will stay one until the current through it is stopped by some other means. SCRs work great as a speed control for AC but don't work on DC. There are probably some other better ideas some of the other people can share with you too.

Carroll

schematic

I am using pull up and down resistors on the gates, they do turn all the way off when you test by triggering the hall sensor. any help would be great!