Ericsson r380 how to repair poor or no signal problem

The Ericsson is one of the first smartphone (the second from IBM Simon) but the first advertised as a smartphone. The phone itself has a small li ion battery that after some years will leak and and the leakage will manage to go through the small holes to the other side of the system board and spoil a very important part for the signal. First think to do is to remove the battery with a good soldering iron and then with the hot air gun remove the chip from the other side. To remove the chip, we can use flux and then clean everything (the corrosion on the chip, its place on the systemboard, the flux). Then we resolder the chip but without flux to avoid any current leakage from flux.