Ventilation help needed

I bought a homedepot attic fan(1335 CFM) and put it in a box making it an inline exhaust fan. after about two months of use(just pulling air from the top of the room)--- and the same day I hooked up my new 1000W MH light with vents to it. it died. and it wont come back to life....

I am going to take it back asap.

But I need help with figuring out what the problem was-- and what the solution will be.

1) Why did it die? heat failure???? i thought for being an attic fan it would be used to the temps...

2) Should i get another of the same fan($90) or another type? I was checking out the 8 " inline fans 500 CFM on htg for $49. I can't figure out what the difference between those and the Can fan 585CFM for like $169!!

BTW i am operating in a bedroom- 10 x14x8=1120 CFM
i cant close my door without an exhaust--- and barely could close it with the old fan on 24/7. Should these fans be used as an ALWAYS ON?

All in how the fans operate. If your fuses are good then the motor burned out, its meant to exchange air from one wall to another outside. Those 8in 500 cfm duct fans work great and yes, the expensive fans are mostly worth it. Its not about "free air" cfm its how much torque the fans have to push air around corners and through filters and that you have to pay for.

but the duct booster fans work fine