problems with Bosch built in single oven HBN3550GB?

I cleaned my 7 year old oven with oven cleaner the other day and think I squirted some in the fan. I used the oven afterwards and it was fine twice and then yesterday had a casserole in at a low heat and a continuous alarm sounded and there was smoke pouring out of it - had condensed into steam and actually melted some of the stickers and has stopped the clock/timer from showing full digital figures. It is working still so today decided I would try oven on a high heat - 240 and when it got up to about 200 smoke started belching out again - please advise whther i can do anything to fix it-cheers