How to flash or unbrand lumia 930 and resolve the second mic issue?

[Windows Central Question]

I have lumia 930 that i have purchased recently(used), when ever i switch on my phne vodafone sign appears for a while i want to unbrand my lumia. Secondly it has a mic problem i cant talk to anyone via skype or on call when i turn on the speaker... i have tried windows recovery tool, hard reset soft reset, many of people resolved the same issue with denim update but my phone is already denim updated and some have resolved by flashing the firmware.... I tried flashing with Nokia care suite but data package error occours... kindly help me. any tool or any other procedure that works.