These early generations needed a FastBoot cable to do get into some pre-boot stuff, IIRC. There isn't an easy way to get into Recovery that I've seen. You might be able to talk to it with a regular USB cable and the ADB tools since it's already in a weird state, but don't be too surprised if it doesn't work.

I've got the dreaded boot loop on the original Kindle Fire. I can't seem to find any method that works online to reset it. Held power button many times etc but I can't get past the Kindle Fire loading screen and then it just reboots. 

There's no volume button on these to boot into any recovery. Is there anything that can be done with ADB or the likes?

Original Fire D01400 - Boot loop