have you tried other USB flash drives?
please try to disable secure boot too from BIOS
https://us.answers.acer.com/app/answers/detail/a_id/27071#_ga=1.171795040.1726682513.1446488832
have you tried other USB flash drives?
please try to disable secure boot too from BIOS
https://us.answers.acer.com/app/answers/detail/a_id/27071#_ga=1.171795040.1726682513.1446488832