Didn't you say that?
In any case there's a few things. When you installed the BLW did you clean the connector of the NES system board before attaching it? Most people only clean the cartridges but the system has a connector too which can oxidize. Also, did you check the solder connections on the BLW? I believe it's two connectors just soldered onto a PCB, maybe the connectors weren't soldered well. Maybe the connectors on the BLW need to be cleaned too, maybe they wear quickly as I don't know the quality of the parts used in these.
Also with the new caps not reading at the correct values, doesn't this usually happen when caps sit around for awhile, but they charge back up to their correct values when put into regular use? Honestly I forget the details on this.
If it's not powering up at all now, maybe you damaged it in someway while soldering? With no power it does sound like it could be the voltage regulator, usually these don't need to be replaced unless you plugged in the wrong adapter or had a power surge.
Personally I found a specific cleaning kit made by Gemini to be the best at cleaning console connectors, but it's sadly difficult to find. Even original NES connectors work like new after I spend time cleaning them, and I also use the kit to clean other consoles like the Gameboy/GBC/GBA, SNES, and Genesis. Every system that uses cartridges needs the connectors to be cleaned eventually, even on PC motherboards.