Im having trouble replacing the oven door hinge?

I have a Flavel Finesse 100 FN10 FRS
Just before Christmas the top door hinge on the fan oven broke (the pin had sheared in half) I brought a replacement online, which arrived today & I thought screwing the new one on, in place of the old one would be a doddle...
However, the screws wouldn't bite & it seemed a plate, into which the screws go, behind the front panel had slipped out of alignment...
I cant see how to get it back into place. Will I need to take it all apart & if so how? Please, this has driven me bonkers all morning. Thanks