I recently (meaning last night) fixed my Toshiba Tecra 8100
by installing various new parts I spent over a year trying to find.
RTC Battery, LCD screen, Motherboard and inverter board.
Once installed I still found myself having trouble booting until I thought of switching the laptop memory card from one slot to the other.
The computer finally booted up but had trouble staying on. Various software error messages about Windows confirming licensing or errors in reading and implementing .exe and .dll files.
After another half hour of reboots; another idea came to me.
Maybe there's a shorting going on between the metal casing of the laptop; the metal casing of the heatsink fan and the CPU.
Replacing the metal cover with ordinary scrap paper to make sure the "air" still flows out the vent remaing constant.
For all you Toshiba Tecra 8100 users; there's my notes on a successful repair job.
(p.s. before coming up with the idea to remove the tin casing from the heat sink fan I still had trouble booting when it cut out seconds after pressing the power button and typing in my password in the pre-windows/DOS like prompt - disconnecting and reconnecting the CPU along with the RTC battery helped guide me from A to B.)