My Kindle fire is refusing to restore

I have been heavily modifying my Kindle fire 3rd generation and now it's biting me in the *** because now it's refusing to restore or update. The tablet is very unstable, programmes are refusing to open or uninstall, just a mess. The worst part is I can't restore it. Every time I click restore it will just hang on the Kindle fire logo and do nothing else but get alarmingly hot. Their is also an update available but the same thing happens hangs on Kindle fire logo and gets alarmingly hot. Any suggestions that could solve this issue that don't include smashing it and buying a new one?

i don't want answers like "just reset it" or "go into settings and restore it" i have tried both and don't work. helpful answers only please. sorry if i seem rude.