have noticed a few people with the same issue upon downgrading from iOS 11 beta 2 to iOS 10.3.2, in which trying to restore it becomes a endless loop of getting stuck at the recovery mode on the iPhone. I have found a potential way of fixing it. So if you are currently stuck in that recovery mode and its not going anywhere update your iPhone with the IOS 11 beta 1 via selecting the .ipsw. Once that has completed set up your iPhone but do not sign into your iCloud (note you can sign into wifi). Once you have set up your iPhone connect your iPhone to your computer. Then restore to iOS 10.3.3 from your download .ipsw file, set up your phone once more. After that restore agin to the iOS 10.3.2. Then it is recomended that you set up the iPhone but do not sign in quite yet but to confirm that it is at the correct version of iOS 10.3.2. After it has been confirmed factory reset your phone then set it up like normal. Congratulations you are back to iOS 10.3.2.
What you will need:
iOS 11.0 ipsw (restore image)
iOS 10.3.3 ipsw(restore image)
iOS 10.2.3 ipsw
(please note I am on a iphone 7, you will have to select the correct files for your device)