Thank you for pictures.

CPU is rated at 3 MHz, so in MM V it is overclocked by approx. 65 %... Not unusual for devices designed by H&G. And not likely to cause the problem.

Yes, some solder eyes look odd.

Ideas:
Incompatibilty with your modular board. Try another one if possible.
Eprom could be corrupted.

Do you have other modules oder chess computers with 65c02 inside? If you buy a CPU on ebay... you don't know whether it is working or faulty.

I would try:
another modular board
new Eprom
another CPU

In this order.