For nokia 1100 not charging (eventhough charger insert) :
1. Check / clean charger connector
2. Check / replace fuse
3. If the problem not solved, trace charging circuit for broken circuit
4. If the problem not solved probably UEM (Universal Energy Management) broken/fail.
5. Replace UEM, Rebuilt imei and tuning Energy Management.
Note : for nokia 1100 uem glued, so it hard to replace, should not to replace UEM.