I bought mine a year or two ago, no problems with igniters or doors or boom while cooking. I do get the boom after the oven has been turned off and is cooling down. I assume it is due to contraction of the metal, but don't think it is a safety issue

I have an older Bluestar, and replaced the door several years ago with the upgrade. So, if you broiler lights with a boom... this means that the glowbar is worn out, OR that it's not aligned properly - even a silly millimeter might cause a delay of ignition-and you have your boom!

If you had the broiler looked at recently, you need to call back the repair person pronto and get it fixed. It's not rocket science, as they say.

Next, the oven pop when cooling.....This is likely caused by the expansion of the steel oven walls and is not unheard of in all ovens- that is -it may be normal.

Its possible the oven floor doesn't have a reinforcement under it (actually a baffle for the heat). Possible but you can take the oven floor out and turn it over and check if it's there and welded securely.

The only rivets used in a Bluestar are to attach side supports to the wall, that support the same oven floor. New rivets can easily be installed if they are lose or broken. You can borrow a rivet gun (you just squeeze it like a pair of pliers) and buy some rivets about the same size (cheap).. However I don't think that's where you're getting the oven 'pop' from.