Yes. That's what I've done several times. The four I listed before (and below) are the ones that persist...
C118C 0109 ABS EV/HEV System BRC-126
C1A6E 0109 Brake EV/HEV System BR-146
C1A70 0109 BRAKE Brake control system BR-160
P31E1 000B EV/HEV HV System Interlock Error EVC-305
According to the service manual, P31E1 is caused by:
High voltage harness
Harness and Connector (Connection detecting circuit within Li-ion battery)
Steps to diagnose:
1) Ensure the service plug is installed and seated properly, and has not come loose. It's located underneath a panel in the floor between the two rear seats.
2) Turn off car and wait >30 seconds. Check 12V voltage is 11V or more. Personally, I'd make sure it's 12.4V or more.
3) Check the high voltage connector harness to the battery.
4) Using a 500V DC meter and HV gloves, check that the HV terminals on the battery read 5v or less.
5) Visually inspect, check continuity of HV cabling harness from end to end, and replace if problems are found.
C1A6E - Indicates a malfunction in the VCM system, caused by a failed VCM, harness or connector, or the electrically driven brake unit
This code recommends, again, checking the 12v battery voltage and multiple steps with the consult tool (which you don't have) to test the brake controller.
C1A70 - Indicates a malfunction in the intelligent brake controller or harness
Again, this recommends checking the 12v battery and then a bunch of diagnostic steps of the brake controller with consult.
I see nothing in the service manual showing these codes trigger each other, but I can't rule that out either. This post showed someone with all the same codes you have:
Unfortunately, that person has never posted with the root cause on those codes.
A couple thoughts:
1) The common failure point is the 12v battery. However, you've sworn up and down it's charged, provides good voltage, etc. Double check the battery terminals, make sure there's no corrosion, etc.
2) Another problem that has come up on the forums is the pre-charge resistor, as posted by Leftiebiker. This may be it, as this guy has EXACTLY the same 4 codes you do, and diagnosed it as a failed resistor in the pre-charge circuit, which is located inside the battery:
If your pre-charge circuit failed, the failure may still be under warranty. Battery warranty lasts 8 years, 60k miles. If you have <60k miles, you might be able to get a new battery out of this...
Be careful not to void the warranty doing work on your own, in case this is the failed component...
3) If #1 & #2 aren't the issue, you're really going to need the consult tool to get to the bottom of it, or start randomly checking connections, wiring harnesses, etc. Because all of the codes involve CAN bus errors (the P31E1 from the BCM--battery), and the rest from the brake controller, I would start checking the can bus wiring from the battery and the intelligent brake controller to the VCM. A disconnect or problem with the CAN bus could cause all of these errors. The primary CAN bus in the leaf has the VCM, DLC, BCM, ABS, Steering, and Dash/Nav. You fault codes involve the VCM, BCM, and ABS, all of which are on this bus.
So, in short, I think diagnosing with Consult is the way to go, but you've said you really don't want to spend $600 at the dealer for a possible non-fix. Given that, I would start checking electrical continuity between pins between BCM, VCM, and ABS. As always, given the BCM is located in a 400V+ battery, be careful in case there's a short somewhere and there's high voltage somewhere you don't expect.
If you go the self-repair route, you're going to need the service manual. Everyone on this forum has given you the common cause (low 12V battery), but you've pretty clearly stated that it's not your issue. Therefore, some detailed debugging is in order.
Best of luck.