Help asus K55A series

i have recently got a asus K55A laptop on windows 8 and i want to update it to windows 10 because the laptop has startup problems and lagging issues so i need to get windows 10 but i was in the middle of installing windows 10 on my laptop
via the windows 10 update assistant but it does everything restarts then gets to the part of the blue screen just installing windows 10 still then it goes to the asus screen and freeze's is there a fix for this any help is appreciated thank all who reply to this thread