My M8 will only charge when powered off and no USB

I have a M8 which will only charge when powered down or in fastboot AC.
When off it shows a battery with a power symbol, it does not show the charge level. and it keeps restarting.
When I boot into fastboot and connect a charger it shows fastboot AC and it starts to draw current, around 1A.
Also fastboot USB fully works so I can flash.
When I boot the Phone it won't recognise any USB connection, either PC or charger.
I have already replaced the USB board. Factory reset, battery recal.
Everything else works.
It happened after the battery was fully discharged when the Phone was not used for a time.

Kernel logging does not show any USB detection, I am now looking into the kernel source to try to understand how USB detection works.
I don't understand that hboot/fastboot seems to work fine but when booted USB does not work.

Any hints where to look or what to test are welcome.