I got the new board installed and checked, it did not work.  I double checked that the solder is making connection to the board from the cart connector.  (vias will be covered in final version)

When I used BRAM tool, it reported no BRAM.  When I used TurboGrafx-16 CD System 2.0 card to access memory backup, I got corrupted display instead.  When I used PC Engine CD 2.0 card for the same thing, I was able to enter BRAM area to delete and format but the text is corrupted.

I need to find my microscope to verify all the pins on HuC6201 is soldered and not accidentally floating.  The game I selected at random played fine with the board installed so there's no interference.  If those microscope check didn't find any error, I'd need to try a second HuC6201 chip I have to rule out defective chip.

I really wish there were more documentation on HuC6201 beside the pinout, it'd be so much easier to troubleshoot this or clone the chip with FPGA or something similar.