Weird thing. The kb + mouse seems to work fine, I press DEL or TAB and I enter the AMI bios, which then asks me to press DEL or ESC to enter bios (again?), but at that point the kb is not working! so no BIOS for me.
After a bit, lubuntu boots and kb+mouse works fine.
I understand power is usually an issue, but I bought a purpose-made minibreakout board and PSU, so I should be in the clear.