求助: Toshiba A105 不正常关机后无法启动

I have a Toshiba A105 laptop. No battery connected. Yesterday I lost power accidently. Now it won’t start. Following are the symptons:

When I press Power button, On/Off green light up. 3 seconds later turn off. And Caps Lock key and two green light above number 9 and number 0 key flash. Five times it automatically turn off.

I know it can be turn on by pressing down certain keys when it just start, but not sure which key. Anyone knows?

Thank you so much!