Win98 Installation

I tried installing win98 over a an already existing version that I had trouble with and couldn’t solve. The installation went fine until windows requested to restart the computer. The computer restarted normally, then I got the message “You are in MS Dos mode do you want to switch to windows mode? Y/N”. If I answer yes then the computer goes into loop and if I answer no it goes into Dos mode and wouldn’t start windows. what could be the problem? And I don’t want to format the HDD and make a clean installation.