Had to tear the unit down, do plastic welding since the screw mounting slots broke.
Probably I would rate this as a 0/10 in the reparability scale by myself -_-.
Also, bypassed the 10 V regulator on the charger boost converter module and now it can work from 9V.
Planned to add another separate boost converter for the inverter to prevent inverter’s low voltage protection from kicking in.
Bypassed the regulator here as well. I feel kinda lazy and tired, probably will log more time from tomorrow,,