This board was given to me as faulty in a deal.
Upon power up game was stuck on a garbage screen:
I quickly noticed work RAMs were shiny ones (known to have a high failure rate) but I dumped the 3 program ROMs first: they matched the Japanese rev.1 romset in MAME. Probing the RAMs didn't revealed anything weird but by using the oscilloscope I could "see" main CPU was sending data cyclically. Cleary no valid code was executed and CPU was stuck in a loop. I pulled both work RAMs and both tested bad on my programmer. After replacement game booted mostly fine, with sound, texts and background but sprites were replaced by big misplaced blocks of garbage: