Troubleshooting Emotorwerks Juiceboxes

Willie had two old Juicebox units laying in a pile in his Partybarn, and suggested I might look at them to see why they don't work.  Both were 60 amp units which means the wiring would handle 14,000 watts.  (BIG cables...the size of garden hoses!)
Here is a YouTube titled EMotorWerks JuiceBox Premium - a Build Manual
This is the exact unit.  https://youtu.be/SScYZKV7iDc


My first step was to open both of the units and look for any obvious damage, but both are very clean inside and there is no evidence of any burning or overheating.  The cables were another story, with a heavy layer of black grime, calling for a spray bottle of cleaner and a Scotchbright pad.  Now they look like new cables.
On to the power plugs.  One is sealed, but the other had screws and when I inspected the internals, the ground prong was bent so the little screw could contact the big black 240 volt prong (internally).  I removed it and bent it back into shape, and for good measure, cut about 1/8" of extra length from the green ground screw.  I saw no evidence of contact beween these two lugs, but perhaps the main circuit breaker popped before anything melted.  Maybe nothing ever happened...
One of the J1772 plugs is nice and clean.  The other looks like it had been under water for some time, with some green gunk and corrosion present.  Not sure how to clean those pins.  They are probably crimped with a very powerful crimping tool.  (Back to this later.)
The internals of these two units are similar.  A big relay, an OEM 220 vac power supply that supplies 5 and 15 volts to an Arduino circuit.  Not sure how to handle the Arduino, but if I apply power to the power supply, the voltages could be measured at the output.  I have a 120 to 240 volt transformer that I could use to energize that supply without dragging the whole works out to the barn.
I found this on the Tesla Forum:

stephen.kamichik | July 1, 2014

I have been charging my model S and my wife's Smart Fortwo EV with a Juicebox. Here are some troubleshooting tips:

1. Verify voltage at AC terminals of the power supply. The built-in LED in the power supply should illuminate.

2. Verify +/-15V and 5V at the output terminals of the power supply and at the appropriate input terminals of the main PCB.

If step 2 fails, you probably have a defective power supply. If steps 1 & 2 are good, the main board is probably defective.

I have added POWER ON and CHARGING indicator lights to my Juicebox.

if steps 1 & 2 pass, verify that there is 12 volts at the relay coil. If yes, then the relay is probably defective.

So, those are my next steps.

Checking to see if it will work on 120 vac:  (The sure way is to look at the label on the OEM modular power supply inside the unit, but I found this.)
Jan 2020 comment from manufacturer regarding 120 vac operation: 

The JuiceBox Pro40 models are rated to work with both single phase (240V, 50hz EU) and two phase (240V, 60hz US). For both of these applications, the hot/live wire is tied to L1 on our relay.  The neutral/common for single phase EU is tied to the L2 of the relay, and the ground/earth is to the same.

For single phase, US 120V operation, the JuiceBox will not detect the lower voltage and will not work.