HXPS 9350 wont boot

Hi, my 9350 has stopped booting and gets stuck in repair mode or on the windows logo screen.  It's started acting strangley a few weeks ago when mouse buttons stopped working (the trackpad works fine) and just wouldn't boot.

I've done hardware diagnostics and everything is fine (except the battery that needs replacing) but just can get it to boot no mater what I do.  As a final measure I tried to reinstall windows 10 using a bootable USB but can't get that process to start.  I even tried removing the harddrive and formatting and also trying with a diferent hard drive but nothing seems to let me boot from USB.

Any ideas?  My fear is that the motherboard has gone as i've heard it's a common problem.

Thanks