how to reset it please?Also try reseating the multi and make sure it’s correctly orientated by checking the text on the PCB.
Plugging it backwards didn't damage anything on the multi.I am sorry but I dont understand how you fixed yours system? What's the little little green pcb without screen?
Its the next socket near 68k ...near that 20mhz crystal, near the connector where you put the cable for Frank’s lcd screen selectorthx where is it on motherboard the MCU 87C51?