I’ve had the laptop apart a few times, followed videos, looked at the manual, and was quite careful. It was not easy getting replacement MBs..the used ones come from China and one source didn’t even send me back an unworking MB I returned to them and did not respond to emails. Toshiba themselves don’t even give support for this former top of line laptop. Yes I know about the delicate ribbon and other connectors. The keyboard one I had to get microsoldered back to the board and while at it they notice and replaced a broken resistor. I suspect a connection even though I’m quite sure I did that right but it is possible also that the replacement board is a very slight different revision number and maybe the Bios wouldn’t match. I’m actually thrilled how much I did get working since a major computer store here just said the MB is gone after charging $100 to look at it and another actual expert couldn’t fix it and because of that didn’t charge me anything. It had originally just crashed in the middle of a Zoom call. In the meantime I bought another new laptop so this is just my spare that I won’t sink any more $ into.