Nokia 7510s Not Charging Solution
make a continuity check on the fuse by using a multimeter, replace it if found damaged.
Check the chip diode if shorted or not, a shorted diode will make the fuse blown out again.
If the chip fuse and chip fuse is working fine and found out that there's no problem on both it, you may proceed to work on the betty IC,
The betty IC holds and control the charging operation of the cell phone battery.
Re-flow and apply a mild heat first on the betty IC, then check again if the problem was solved.
If the problem still exists, remove the betty IC, trace the corresponding solder ball bumps that is connected to the filter coil (power inductor). If found cut or open and you can manage to apply a jumper wire, then do it, if won't not just leave it and return it to the owner..
If the said line paths is okay you may re-ball the betty IC then in-place and mount it back again.
If the problem still persists, you may then find a new replacement spare betty IC and replace it.