it is not mpu board. i believe the damage was done after my inline filter fried and filled the the inside of the cabinet with smoke and soot. is it easy to check if its the connectors? is it easy to repair or replace connectors?

Just pull of the connectors and check the pins for dirt or corrosion.
You might have to remove the board from the machine and clean the contacts, if they are only tarnished or dirty, then a regular white pencil eraser works great, if there is corrosion then you might need to use some wet rub 600 grit to clean the contacts.

You can get the new pins for the connectors from any electronics store such as Jaycar.