Nokia 5800 Xpressmusic Charger not supported repair guide
The picture below shows the location of BTEMP thermistor which valued 47Kohms and connected to the BSI (battery size indicator) of a battery connector pin, this component holds the battery indication during charging operation process. Once this said thermistor become unstable or faulty, it will result to charger not supported shown on a LCD display screen. The only solution is to replace this component with the same value as indicated.
The BSI capacitor which is located near to the battery BSI connector may cause the problem if faulty or unstable. Replacement is also necessary.
If problem still exist after replacing this parts a deep troubleshooting analysis is required, The first step is to reflow or rework the integrated circuit (IC)chips which is where the charging circuits lines connected across to it.