After a lot of test and failure including wrapping the battery with aluminium foil lol, I finally found a solution. What option did I have? at least it solved the problem that gave me headache.
The problem with Phones rocking Zero lemon accessories loosing signal lies mainly in the TPU CASE.
If you take the case off with only the battery left, everything works just fine. But bring back the TPU CASE and you are back to stone age.
Straight to the point; I overcame this issue by
1. Removed the TPU CASE and battery to expose the back of the phone
2. Located the phones antenna. Which lies in pair to the right and left of flash light.
3. Measured the distance of the antenna from the flash light to the end of the antenna which is about 2cm from the flash light to the end of the antenna on both sides of the flash light.
4. I now transferred the measurement using a ruler and a pen to the back of the TPU case.
5. Starting from the hole provided for the flash light,With a RAZOR I cut a rectangular shape out of the case.
6. With the flashlight hole as the reference point and center, I cut a tangent 2m above and below the flashlight hole to it right and left respectively to expose the two antennas.
7. A vertical height of 0.5cm for the rectangle and 4cm for it horizontal length. Giving 2cm to each sides of the flash light hole.
This pretty much solved my signal lose. I Hope it solves yours for you too.