The barman

Hi, I’m new here so please be patient with me. I have an Audi A4 2.0 tdi 140 cabriolet that suffered a blocked dpf. Driving from the city one evening the egr pipe split and was the only point of exit for the exhaust gases therefore became very hot and started to melt the engine cover and brake vacuum pipe and also warmed up some of the wires above the turbo/ exhaust manifold. I pulled in and turned the ignition off but the engine did not turn off, even with the key out of the ignition. I’ve since had the dpf removed and the ignition switch replaced but the problem stil persists. The car is in limp mode and P0653 is coming up when plugged into diagnostics. I’m about to check all fuses and relays tomorrow but was wondering if anyone else has suffered similar problems. Any help or advice on this would be gratley appreciated.