If they are using normal FET and not logic one that operates on very low voltage, and your battery can't supply enough current so it drops voltage, that can easily burn the fet. If it dies, it short circuits it's contact.
I was going to buy a bolt but was warned off them so I bought a g&p force recon m4 which has a good recoil system for around the same money as a bolt.
My mate couldn't put it down when I took it to the gun club(I think he wants one hehe)
Update got my money back NOT from the retailer but from my credit card company under section 75 and there now after there money back from the retailer winner winner chicken dinner
Update got my money back NOT from the retailer but from my credit card company under section 75 and there now after there money back from the retailer winner winner chicken dinner