Marshal Major II bluetooth battery is not charging

Recently the battery stopped charging ( no red indicator ) everything else is still working fine, but no charge. No red led, no dim white. One weird detail is that when I try to charge the headphone with bluetooth on, it shut down immediately ( some sort of power protection ? )

Here are the things i checked:

• USB connector: I connected to 5v and measured 5V on the PCB => seems fine
• fuse : I measured a very low resistance => seems fine
• battery : i unsoldered and charged it with a separate Li-ion charger ( seems ok ). I then measured potentials and found ( GND:0V, NTC:0V, VCC:3.7(ish)V ). I also measured resistance between GNC and NTC and found around 10kohm.

I think the problem comes from NTC, but I’m not sure to understand who this works:

• Am I supposed to measure 0.5*Vcc on NTC when the battery is disconnected ? And does it change when the battery is connected or charging ?
• if NTC was malfunctioning, shouldn’t i measure a resistance of 0ohms of infinite resistance ?

Thanks !