ASF2 Force off XPS 15 9550

Heyup!

I've got a XPS 15 9550 and I've just experienced pretty much the same issue as in this post: https://www.dell.com/community/XPS/XPS-15-9560-battery-not-charging/td-p/7257269 and thought I should check here before I throw this piece of laptop in the bin. Symptoms:

• Yesterday night laptop has randomly shut itself down. Log shows Power Off - ASF2 force off
• Since, it does not power on without ac power
• Battery is showing charging but it's been stuck on 81% whole day
• When I pull the ac plug laptop just powers down immediately
• Bios shows battery as being excellent etc.

I'm fully up to date with Win10 1809 an bios version 1.10.0

I've done the whole power down > disconnect power and battery > hold power button for 20 sec > reconnect all > power up

Done the full diagnostics - all clean

Any sensible diagnostics suggestions other than the catch all "reinstall OS"?