Dead Switch, working RCM

Hy,
i did a RCM X86 install on a at first glance perfectly fine switch (successfuly made 20+ the last months), and messed up.
I checked the solder joints, checked for shorts, all good. A clean solder job in my opinion, so i am not sure whether i caused the fault or whether the fault was already present at the time of purchase.

When i start the switch, i have a black screen (not RCM).
When i start the switch without emmc, i can boot into rcm, but not WITH emmc.
When i am in rcm with hekate payload, all battery stats are at 0%, also the charging current shows 0% (battery is at ~4 Volts).

Did i blow up MT92... or PI3USB or something? There are no shorts, at least I have not measured any.

I would appreciate a little help, thank you!

 

Thank you very much for the quick reply.
The battery voltage is at approx. 4V. I tried it with another fully charged battery, its the same error.

What could be the cause for the 0% in Hekate? I have attached a screenshot to illustrate what I mean.
The switch takes some minutes to load the "Battery Fuel Gauge Registers" Part, maybe its normal, i do not know.

Thx!

EDIT: i saw, that the tide symbol translates to - here. So, not -4V but appr. 4V