When I start up my BC9000, two red lights come on, one on the upper part at the right side and the other on the centre at the left side. After four or five seconds, the left one goes out. All is normal so far. With the single light on indicating standby mode you should still be able to get some response from the keyboard even though there is no tape loaded. The number buttons should work when pressed. I presume that you have absolutely no response at all from the keyboard. Now the long haul begins. I spent about four months getting my machine into full working order and for me, it was certainly a very complicated unit and a hard task. I also had the good fortune that the keyboard was at least giving a response right from the start. If you have the schematics, you do have a good starting point. I have not seen any literature with back to basic problem solving and the manuals do only provide detailed information on specific tuning issues. If you have checked for proper voltages after the power supply you will now have to trace the situation into board 1. That is where the fun begins. Sorry but I cannot offer any more help than that. If you do manage to get the machine to work, it is a beauty and I still use it a lot.
Geoff