After noticing that I had a good number of 36v batteries for various devices, from my 40v Ryobi Lawnmower (Battery is 36v nominal) to some 36v batteries from hoverboards that I had from other projects.
I thought it might be worth it to get an inverter to have a small backup to run some devices should the need arise.

Browsing the internet, I noticed 36v inverters are not nearly as common and typically are a fair bit more expensive in most cases, $100+..
Seeing how this was only for a backup scenerio, I didn't really want to invest in something too crazy that might rarely get used.
While looking around I noticed the Greenworks G-Max 40v inverter (IV40A00) was possible to pick up for much less, $30-$50 depending on where you look and if there was a sale.

(Sample ad photo)

So I picked one up just to mess around with, even though I did not have one of their batteries.
To my disappointment I quickly found out that they actually have 2 versions and the latest version actually expects a special signal to enable the inverter.

(Image post modification so ends have been changed)
Looking carefully you can see that the sample ad photos clearly show a different version that has a simple red rocker switch, 2 indicator lights, usb ports on the left side of the outlet, in addition the cable harness only appears to have 2 wires vs my unit with push button switch, 1 indicator light, usb on right side of outlet and 3 wires for the battery harness.

So I went about looking at how to hack it to work with any matching voltage source.