HP Spectre X360 13-4128TU - no go, 3 white led flash error code at DC Jack - Repair

Here we have an HP Spectre X360 13-4128TU with no signs of life apart from 3 white led flash error code at DC Jack when power button is pressed - a quick test of the mosfets found the battery mosfet shorted - replacing it bought the laptop back to life...