Too early to say for sure what the cause was, the Ohmmu certainly raises questions, especially with other issues presented earlier this month but it's gonna take a lot more detail for a postmortem. That being said, a pop beneath the feet does at least suggest a HVB event occurred, but without granular detail, it's impossible to say which battery is to blame. Apologies for the implication so soon after the fire, I just knew that you were having LVB issues earlier and I was shocked and short on time to write a more thoughtful response.
1) Ohmmu replacement battery
Well the answer SHOULD be you CAN'T, not 'don't."
I agree with you - too early to say for sure, but - "under your feet" is relative - when you're sitting up front, the LVB is right there between the seats, and I could absolutely see that being felt in your feet. The 2 smaller pops sound like the pyro fuses blowing, which would make sense if the LVB exploded and mangled things under the dash which would include front motor wiring and coolant loops.
If it was the 12v battery...then it's on Ohmuu.
Outside of actively charging or driving, the Lightning supposedly only tops up the 12v if it's been sitting at < 40% for 48hrs or immediately once hitting 30%. Then it supplies 300W under either of those. It's amazing that they still have updates fail due to low 12v. It shouldn't be that difficult to trigger a charge event if the 12V is below 80% and the hvb is above X. Also reports of the truck going to sleep and remote start not working? What a joke.
You can do this with a n.co genius charger. The Ohmmu batteries have a BMS that doesn’t register as needing charged by many trickle chargers with current sensing. So they implemented a force feature that will output charge regardless of readings from the battery. In order to charge an Ohmmu battery with one of these chargers you have to use the force mode. This is obviously bad on many different levels.
