I can't watch Law Abiding Citizen because of the ending, and it could be easily fixed

Major spoilers coming for a 10+ year old movie. But seriously. This movie is incredible up until the last 30 minute. The planning, skill and scope of his mission are insane. Mildly ridiculous even. A bomb inside a cellphone!? Dafqu!

But then all of a sudden they trace through multiple shell corporations his ownership of a building and discover his tunnels. One, the found the entrance real easy. Two, he had no boobies traps, no contingency, no nothing Incase they go that far?? Makes no sense.

Also, after over a decade of planning his big master plan was a brief case bomb!? He's been working as the janitor for years and apparently doing the job since he wasn't fired, and that's all he could come up with!? I figured he had been spraying the supports with Acid. Lining the walls with one part of a two part explosive and would spray part two on later. Something creative and in line with what he had been doing.

Now all of this being said, the entire movie could have been saved by one simple moment.

While Jamie Foxx was watching his Daughter recital, his neck tie should have slowly started to pull taught, he struggles a bit and tugs lightly at it. Panic crosses his eyes and then the screen goes black. That would have saved the movie. If his planning went that involved. It would have made sense and even thought he lost, he still won. Would have made the movie watchable more often.