Introduction
A quick and simple guide to replacing the battery in your Marshall MID ANC headphones. Might apply to other models, too.
The replacement battery needs a NTC cable + temperature regulation PCB.
I found this one on Amazon Germany working flawlessly (charging and functioning well since 12/2023):
DC 3.7V 800mAh 603040 Wiederaufladbare Li-Ionen Batterie für Marshall MID Major II Major III Major IV Bluetooth Kopfhörer VDL603040 SR603040
Tools
Parts
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            Unsolder the 3 battery leads. 
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            Solder the 3 leads from the new battery (red=B+, black=B-, white=NTC). 
 
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                            Conclusion
                          
                          To reassemble your device, follow these instructions in reverse order.