4s battery life poor; grounding parts missing

1. I paid someone to replace my iphone 4s screen this summer after I cracked it. Clearly they replaced it with an old or low-quality display. It had a beige spot constantly in one corner of the screen, and developed horizontal banding after a week or so.

2. I got a new screen and new battery from iFixit and replaced them successfully two days ago. Both work.

However, the battery life is still poor. This means:

Fully charged overnight.

9AM 100% charged.

Zero apps running.

Down to 18% by 1PM.

Is this most likely because:

2A. iOS 8.1.1 is very tough on iphone 4s, and I'm just out of luck if I want a full-day charge?

2B. The fact that the "professional" repairer must have lost some grounding parts that could be shortening battery life?

Sostituzione schermo iPhone 4S

Step 5: "Take notice of the position of the small black ground clip" (upon opening, my phone lacks this grounding clip)

Step 23: "One 3.6 mm standoff along the side of the logic board nearest the battery opening." (my phone lacks this standoff)

Step 25: "Be sure not to lose the small grounding finger" (my phone lacks this grounding finger)

Step 35: "Loosen the three large-headed Phillips screws " (my phone has 2 of these screws, not 3)

Step 39: The "professional" did not remove the pink protective backing from the other display assembly he installed :)

Which do you think? 2A or 2B or both?

If 2B, any place I can buy these miscellaneous bits? I did not see them on the iFixit website.

By the way, I also replaced the screen and battery for another 4s, and all of the above-listed parts were there. So I did not overlook or misplace them. They really were lost or stolen by the "professional". Sigh. Live and learn.

What to do now?

Thanks in advance,

Andrew