BQ76930: CAP2 does not reach 3,3V Boot-problem

Hi Sebastian,
In the schematic segments I don't see a couple things needed for operation, they might be there, but please check:
The BAT pin must have a power input filter resistor, typically 1k from the CE10 to VC10X nets. If the resistor is missing the BAT pin should get a voltage R1 and D6 to operate although improperly so this might not prevent CAP2 from coming up.
The power filter capacitors are not shown in the schematic segments. There must be a capacitor from VC5X to GND and one from VC10X to VC5X, typically about 10 uF. Without the power filter caps the part may not work properly.
REGSRC is shown connecting directly to CE10. A filter should be used (resistor & capacitor), but that should not prevent CAP2 from starting.
It is preferred to have the bottom of C21 connect to GND rather than VC0, see figure 8-2 of the data sheet, but that should not prevent CAP2 from starting.
Be sure RT1 is in place. A voltage across C11 or RT1 will prevent CAP2 from starting. Also I see the net label on TS2, be sure this does not go somewhere in the circuit which is pulling the net toward VSS, that will also prevent CAP2 from starting. Your pull of VC5X to CE2 may be dropping VC5X with respect to TS2 allowing the part to start. Measure the voltage across TS2 with respect to VC5X before booting. It should be approximately 0V. If it is positive or negative it may prevent CAP2 from starting.

Hi Sebastian,
The standard schematic in simple form is in the bq76930 data sheet figure 8-2, notice the Cf caps toward the right side. Of course the data sheet schematic is simplified and the EVM schematic is more complete, see in the bq76930EVM user guide, slvu925 figures 27 and 28. It is easy to miss the Cf capacitors C34 and C35 in figure 28 amid the evaluation features and population options. The TIDA-00449 has the Cf components on the right of its schematic page 2. The application note bq769x0 BMS Configurations for Cordless Appliances available in the product folder also shows Cf caps with 6 cells, (figure 3) but not with external balancing. A couple of these have the non-preferred VC1 capacitor connection noted before.

The voltage difference between BAT pin and VC10 seems to indicate the part is missing the Rf resistor for BAT. It must be the voltage VBAT voltage (BAT - VC5X) for the upper group is collapsing during the boot attempt at lower cell voltages below the VPORA level.
I would guess while it is running and you begin balancing the BAT-VC5X drops into the VSHUT region resulting in the upper group shutting down and the XREADY fault.
The part needs its power connections and decoupling to work properly.