Today I repaired the LB Air unit received by jhonbull,
I wish to share my experience.
the unit was fried.
The broken component was the one at upper right in the picture.

it's a double inductance.
between positive terminal and the load (the LB circuit) there is one inductance.
between negative terminal and the load (the LB circuit) there is one inductance.
this component can be used to filter the input voltage cause the inductance opposes to fast change in current.
this component may get broken if the load becomes too much big (a short circuit[internal or external] or some component drying anomalous current) or if the input voltage changes too much fast (overvoltage due to wrong battery connection or some component generating spikes and overvoltage.
I replaced it with 2 self built inductance obtained with a piece of copper and black silicon.
In order to mechanically reinforce the welding i added silicon all over it and a piece of tap.
I closed everything and now it works again.