I have a Toshiba Satellite c855d-s5116; pscbuu-008008. It runs Windows 8.1.
It was working very normally, until one day the screen went black and the battery wouldn't charge. I've had it for a few years (honestly can't remember what year I bought it) so I figured the battery died, which I replaced. That worked for about a week when it wouldn't turn on and wouldn't charge again. So I figured it was the DC adapter. Bought a new one and it worked fine again for a little while. I don't use it frequently, as it is mostly for travel and/or work related things, so after a few weeks of it sitting around (not plugged in), I plugged it in and tried starting it again, and once again, it will not turn on. When I replaced those items I did so by model compatibility, so everything should be rated accordingly.
I have removed the battery, unplugged it, and performed a "battery reset" as recommended by several troubleshooting pages. The only thing that happens is the same very slow orange blinking LED. It doesn't seem to be blinking in an error code pattern (not sure that even applies to my model), as the light will stay on about a second, then go off for two seconds, etc etc. I then tried removing the battery, resetting it, and only plugging the DC back in (no battery) and that produced a white LED light that would stay on, but if I pressed the power button there seemed to be a discharge and the LED would go out for several seconds (nothing else happening), then come back on.
I'm thinking it has to be an internal hardware problem, I'm just not sure what or how to diagnose it. I don't mind doing repair work myself so long as I have instructions. I do have access to Ubuntu on USB boot stick (I usually dual boot with Ubuntu on my systems but never got around to it on my laptop).
Thanks for any/all help!