ThinkPad Yoga 12 battery charging problems

[Tasurinchi]

Hi!

I have a ThinkPad Yoga 12 that doesn't charge or recognize a battery. I'm quite sure it's a motherboard issue since my almost identical TP Yoga S1 can charge the internal TP Yoga 12 battery without any issues. Needless to say, the TP Yoga 12 won't charge the TP Yoga S1 battery either. So I have two questions:

1) Provided I'm right about the motherboard issue, is this fixable? Like is there any fuse to replace or something similar?
2) How to upgrade the BIOS? This TP has a very old BIOS and with no battery the ISO image and the Windows program refuse to upgrade. Does anybody know a trick? I search the webs for manual commands to bypass it but no luck so far.

Any help or hint will be highly appreciated! Thanks a lot in advance!

T

[RealBlackStuff]

If that battery has the same contacts as T60-T440, make an extension cord as seen here: viewtopic.php?p=680106#p680106 to use a working battery.

[Tasurinchi]

Hi RBS!

Thanks for the prompt reply. I'm not sure if the contacts are the same, these are new type of internal batteries used in newer TP generations. I'm not sure I'll be able to make my own extension cord anyway (actually, I'm sure I cannot )

But you got me now thinking if I could check if other internal battery may have the same connector, I have few xx50 and a TP Yoga 14 batteries somewhere.

EDIT: No luck, the xx50 and TP Yoga 14 have totally different connectors...