You can actually take the dark electronic card before setting the clock, skipping some parts. Looking down onto the wire and spamming "E" allows you to do this.
Ended up hanging above the shield when trying to take the engrenage, and the bots left me to die.
The Egyptian part where you try to take a triangle piece from 2 sliding bars, if you take it at a certain time, it is possible to get stuck and forcing a restart.
Also, how do you take the 2 Magnums behind the Scarab?
What is the difference between finishing the game with/without blowing up the Manor?

@Andreng Thank you very much for your return and your list of constraints having escaped me.
I did not anticipate the spamming E on the black electronic card, I note. The bars of the pyramid will be adjusted. For the gear it is impossible to recover it from above. you have to jump or shoot from the opposite. This is a special case but I can improve that.
Sorry for the unfortunate inconvenience that will be corrected.
"The scarab is revealed through the reflection of the player who will know by chance or deduction where to look."
The goal of L4D2 is to run away.
The key of my point of view on the end is inscribed on the fountain of the medals.

Thanks again for all this and GG