Phone only regains signal upon re-inserting SIM.
Upon being turned on or inserted a SIM card, the phone will have signal for some time and then show no signal bars. It seems to get signal again if the SIM card is re-inserted, network settings are reset, or it's turned off and on and will lose it again after a while. How much time exactly? Not quite sure with what I've used so far, but I'd say it can keep a signal for about 20 minutes. It should also be worth mentioning that another phone at the same location seems to get one or two more signal bars than this phone.
I have tried replacing the antenna and putting the board on another chassis and it was to no avail.
Completely resetting the phone is not an option as I don't have the icloud user's details(and neither does he...).
May be worth mentioning that the phone was a bit dusty inside. In fact, the camera is damaged with gray stains on its image(no, not fixable by cleaning). I don't think it's a coincidence that both cameras that I have seen damaged this way have been from phones that were dusty inside. If I had to take a guess I'd say this debris didn't just damage the camera but the board as well somehow, especially considering that the charging port was also damaged.
Unless anyone has a better take on this?