Toshiba satellite c55d-b5310 not powering on, black screen, cooling fan begins then stops after 5 sec., HDD sounds like it spins but no sounds of "working", no "clicks" of normal operation. Problems occurred after Jan. 15th 2020 windows 10 update, (after 1904 had been running previously), no symptoms before. Power supply tested & good. Tried working extension monitor, nothing. This model has no CMOS battery. Tried ALL combinations of powering off removing battery & power, holding down power button for 60 seconds plugging in then: holding down every function key + shift, control, escape etc. combination after powering down, removing all power & holding power key 60 sec. after every separate attempt. Removed RAM, removed hard drive, removed cd/dvd drive, detached: SD reader/ touch pad & 2nd usb drive. ??? Is my mother board bad? I can't even get into BIOS.