If there's an issue with the power plug then just cut it off and fit a new plug to the cable.
I doubt very much that there's a pcb inside the machine - just a motor and a control switch - either permanently on or pulse.
These things usually have a safety interlock so that they don't run unless the bowl and lid are fitted correctly - the bowl and lid together will press down on a button micro switch - sometimes the plunger mechanism that activates the switch gets broken. You can test for this by pressing down on the switch with no bowl fitted.
I doubt your ability to fix a pcb - you only assume that there's a pcb - and you have not dismantled the mixer to look for one.
Good Luck...
April 2017