I installed ubuntu 16.04 alongside windows 8. Secure boot disabled, CSM boot mode in order to boot from usb. After booting from usb several times, i can not even get access to ubuntu. Windows does not recognize usb or usb installer. I fixed this problem by changing usb installer whenever got stuck.
Ubuntu installed fine on partition dev/sda9. I tried grub2win to boot, but it fails. For ubuntu black screen appears. Windows boots normally.
Also tried boot repair without success.
Main problem is that Ubuntu does not boot. Due to usb installer issue and dummy toshiba UEFI system I have limited access to ubuntu with usb drive only.
I appreciate your help in advance