I have a acer aspire 4738zg pc and when I press the start button it shows 'ACER' then it goes immediately into a black screen with something that looks like an underscore on the top left corner. When I get to this screen, the pc is unresponsive. When I press f8 nothing happens but f2 and f12 work for booting options. I once took it for repairs and had everything wiped and the windows they installed for me is windows 7 ultimate. How do I get my pc to switch on?
Thank you for your help.