Here's a hints on how to fix no speaker audio problem on Nokia C2-03 or C2-06 and C2-08 dual sim card phone.
1) Check the speaker using a multimeter. Replace if already damaged. A distorted audio sounds is cause by a weak speaker... or it is already burned out. (internal coil is damaged)
2) If the speaker is good and seems no problem, ensure that the terminals were not misaligned. Then clen the speaker terminal contact pads for possible oxidation build ups (this might weaken the connection).
3) Check each of speaker+ and speaker- corresponding connection line paths accross to each components where it is being connected.
4) Check all the filter coils and capacitors connected to it. Replace if found damaged or already corroded.
View the larger image
Nokia C2-03, C2-06, C2-08 Speaker Problem Solution