Broken Bolt

Hi all removed egr valve today
but one of the bolts snapped off in the manifold

Tried to get it out but it was siezed solid.
In the end had no choice but to drill it.now i have to buy a tap & die set to re-thread the hole.
anyway i got the blanking plate on with one bolt for now and obviousley its blowing,will this harm the engine in any way?

Not sure, but it may be worth trying to lockwire the un bolted side to stop any distortion of the plate. If not can you clamp it up with a mini G clamp until you can get the thread in?