To hard reset the Karbonn A5 and for pattern lock solution please follow the steps below.
Karbonn A5 Wipe Data/Cache On Fastboot Mode
1) Press Volume Up + Power Button on Karbonn A5 to Enter Fastboot Mode
2) Now Connect the phone to PC using USB Data Cable
3) Let the ADB driver to be install
4) Open the Android Multi Tools
5) Press No. 8 and then press Enter Key
|Karbonn A5 Wipe Data on Fastboot Mode to remove pattern lock|
That's all after completing the process the will be restart and you have successfully unlock the pattern for your Karbonn A5. Remember all data will be lost on the phone storage.
If you want to reset the pattern lock only then you can try Number 4 to reset Gmail only, some time it may not work.